linter: remove dead exclusion rules from .golangci.yml

[pgimalac]

What does this PR do?

Removes several dead or redundant exclusion rules from .golangci.yml:

Duplicate rule (cosmetic):

• Removed a duplicate unnecessary conversion exclusion that appeared twice.

Dead unused suppressions (task #10):

• `eventContext` is unused — symbol no longer exists in the codebase.
• `(*DatadogLogger).changeLogLevel` is unused — changeLogLevel moved to *loggerPointer during a refactor; the original type no longer has this method.
• `defaultRetryDuration` is unused — symbol no longer exists.
• `defaultRetries` is unused — symbol is used; the linter wouldn't fire on it regardless.

Dead errcheck exclusion:

• pem.Encode — the file that motivated this (test/integration/utils/certificates.go) was deleted in Remove the agent_integration_tests GitLab job as it doesn’t run any useful test anymore #39772. All remaining live pem.Encode call sites already check or explicitly ignore the error.

Dead revive exclusion:

• exported const APIName — the constant no longer exists in pkg/serverless/trace/inferredspan/; the file is also already globally excluded via the paths list.

Stale comment fix:

• Updated the comment on the io.WriteString errcheck exclusion — its originating file (tools/dep_tree_resolver/go_deps.go) was deleted in Clean unused file, task and module #22067. The rule itself is kept as it still covers unchecked writes to http.ResponseWriter.

Motivation

Dead exclusions accumulate noise in the config and make it harder to reason about which rules are actively suppressing real violations.

Describe how you validated your changes

Ran dda inv linter.go — 0 issues.

Additional Notes

Part of a broader linter configuration cleanup pass.

[dd-octo-sts]

Files inventory check summary

File checks results against ancestor 0da860ec:

Results for datadog-agent_7.80.0~devel.git.221.e6eb278.pipeline.109825008-1_amd64.deb:

No change detected

[cit-pr-commenter-54b7da]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 312c6dc8-a1f3-4365-afc3-2f8d4b0bf9e2

Baseline: b3132ad
Comparison: 9a4ab33
Diff

Optimization Goals: ✅ No significant changes detected

Experiments ignored for regressions

Regressions in experiments with settings containing erratic: true are ignored.

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	docker_containers_cpu	% cpu utilization	+2.70	[-0.36, +5.77]	1	Logs

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	docker_containers_cpu	% cpu utilization	+2.70	[-0.36, +5.77]	1	Logs
➖	quality_gate_logs	% cpu utilization	+1.88	[+0.25, +3.50]	1	Logs bounds checks dashboard
➖	otlp_ingest_metrics	memory utilization	+1.33	[+1.18, +1.48]	1	Logs
➖	uds_dogstatsd_20mb_12k_contexts_20_senders	memory utilization	+0.30	[+0.25, +0.34]	1	Logs
➖	ddot_metrics_sum_delta	memory utilization	+0.29	[+0.12, +0.47]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	+0.28	[+0.25, +0.32]	1	Logs bounds checks dashboard
➖	tcp_syslog_to_blackhole	ingress throughput	+0.20	[+0.04, +0.36]	1	Logs
➖	ddot_metrics_sum_cumulativetodelta_exporter	memory utilization	+0.13	[-0.10, +0.37]	1	Logs
➖	file_tree	memory utilization	+0.06	[+0.02, +0.11]	1	Logs
➖	ddot_metrics	memory utilization	+0.04	[-0.15, +0.23]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	+0.03	[-0.37, +0.42]	1	Logs
➖	ddot_metrics_sum_cumulative	memory utilization	+0.02	[-0.14, +0.18]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.02	[-0.48, +0.52]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.11, +0.11]	1	Logs
➖	uds_dogstatsd_to_api_v3	ingress throughput	-0.00	[-0.21, +0.20]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	-0.01	[-0.11, +0.09]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.02	[-0.22, +0.19]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.07	[-0.50, +0.36]	1	Logs
➖	docker_containers_memory	memory utilization	-0.08	[-0.18, +0.02]	1	Logs
➖	quality_gate_idle	memory utilization	-0.11	[-0.16, -0.06]	1	Logs bounds checks dashboard
➖	ddot_logs	memory utilization	-0.36	[-0.42, -0.30]	1	Logs
➖	otlp_ingest_logs	memory utilization	-0.38	[-0.48, -0.29]	1	Logs
➖	quality_gate_metrics_logs	memory utilization	-0.57	[-0.83, -0.32]	1	Logs bounds checks dashboard

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	observed_value	links
✅	docker_containers_cpu	simple_check_run	10/10	691 ≥ 26
✅	docker_containers_memory	memory_usage	10/10	241.70MiB ≤ 370MiB
✅	docker_containers_memory	simple_check_run	10/10	721 ≥ 26
✅	file_to_blackhole_0ms_latency	memory_usage	10/10	0.16GiB ≤ 1.20GiB
✅	file_to_blackhole_0ms_latency	missed_bytes	10/10	0B = 0B
✅	file_to_blackhole_1000ms_latency	memory_usage	10/10	0.21GiB ≤ 1.20GiB
✅	file_to_blackhole_1000ms_latency	missed_bytes	10/10	0B = 0B
✅	file_to_blackhole_100ms_latency	memory_usage	10/10	0.17GiB ≤ 1.20GiB
✅	file_to_blackhole_100ms_latency	missed_bytes	10/10	0B = 0B
✅	file_to_blackhole_500ms_latency	memory_usage	10/10	0.19GiB ≤ 1.20GiB
✅	file_to_blackhole_500ms_latency	missed_bytes	10/10	0B = 0B
✅	quality_gate_idle	intake_connections	10/10	3 ≤ 4	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	141.74MiB ≤ 147MiB	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	3 ≤ 4	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	465.62MiB ≤ 495MiB	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10	3 ≤ 6	bounds checks dashboard
✅	quality_gate_logs	memory_usage	10/10	182.26MiB ≤ 195MiB	bounds checks dashboard
✅	quality_gate_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_metrics_logs	cpu_usage	10/10	353.57 ≤ 2000	bounds checks dashboard
✅	quality_gate_metrics_logs	intake_connections	10/10	4 ≤ 6	bounds checks dashboard
✅	quality_gate_metrics_logs	memory_usage	10/10	411.80MiB ≤ 430MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_metrics_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.