Only run smoketests in PRs targetting main repository

[grvillic]

Context

We already have the setting in place to avoid executing workflows in any forked repository without approval from a contributor, but this setting hardens that check to ensure this agent pool is never executed outside of our primary repo. To reduce changes of manual error.

[Copilot]

Pull request overview

This PR hardens the Smoke Tests GitHub Actions workflow so the self-hosted agent pool is only used when the workflow runs in the primary microsoft/component-detection repository, preventing execution in forks.

Changes:

• Add a job-level if guard to skip the smoke-test job unless github.repository matches microsoft/component-detection.

[github-actions]

👋 Hi! It looks like you modified some files in the Detectors folder.
You may need to bump the detector versions if any of the following scenarios apply:

• The detector detects more or fewer components than before
• The detector generates different parent/child graph relationships than before
• The detector generates different devDependencies values than before

If none of the above scenarios apply, feel free to ignore this comment 🙂

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.0%. Comparing base (62ce022) to head (ba3fc3c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff      @@
##   main   #1736   +/-   ##
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