Fix perfsprint lint: replace fmt.Sprintf with string concatenation in git.go

[Copilot]

The lint-go CI job was failing due to a perfsprint violation in pkg/cli/git.go.

Change

Replace unnecessary fmt.Sprintf with direct string concatenation:

// Before
"api." + fmt.Sprintf("api.%s", host)

// After
"api." + host

Original prompt

Fix the failing GitHub Actions workflow lint-go
Analyze the workflow logs, identify the root cause of the failure, and implement a fix.
Job ID: 67083185060
Job URL: https://github.com/github/gh-aw/actions/runs/23093930698/job/67083185060

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[Copilot]

Pull request overview

Fixes a Go lint failure in the lint-go GitHub Actions job by replacing an unnecessary fmt.Sprintf call with string concatenation to satisfy the perfsprint linter.

Changes:

• Replace fmt.Sprintf("api.%s", host) with "api." + host when building GHES allowed domains.

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