Telemetry test fixes

[andrewlock]

Description

• Removed TELEMETRY_MESSAGE_BATCH_EVENT_ORDER scenario
  • There are now no ordering requirements
• Added basic (replacement) test for message batching to default scenario
  • Just asserts that message batching is being used
• Fixed telemetry_app_started_products_disabled scenario
  • The scenario was not correctly disabling APP_SEC
  • The secenario was incorrectly asserting that no products object is provided on app-started
• Added additional requirement on app-started with message-batch
  • app-started should be the first message in the first batch
• Fixed using incorrect metrics variable
  • DD_TELEMETRY_METRICS_COLLECTION_ENABLED is not the correct variable

Motivation

After discussing with @mehulsonowal, this addresses a number of bugs and changes

Workflow

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3. Work on you PR until the CI passes (if something not related to your task is failing, you can ignore it)
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Reviewer checklist

• Check what scenarios are modified. If needed, add the relevant label (run-parametric-scenario, run-profiling-scenario...). If this PR modifies any system-tests internal, then add the run-all-scenarios label (more info).
• CI is green
  • If not, failing jobs are not related to this change (and you are 100% sure about this statement)
• if any of build-some-image label is present
  1. is the image labl have been updated ?
  2. just before merging, locally build and push the image to hub.docker.com

[andrewlock]

AFAICT the failing tests are unrelated to this change (the python tests were failing previously, the otel tests are a 429 from the backend, and the node tests were dsm-related

[pawelchcki]

Looks good to me but - it could use a second look from @DataDog/telemetry-and-analytics