Update test cleaner workflow to delete branches with prefix test-safe-outputs-custom-engine/

[Copilot]

The test cleaner workflow was not cleaning up test branches created by the test-safe-outputs-custom-engine workflow, leading to branch accumulation over time.

Problem

The test-safe-outputs-custom-engine workflow creates branches with names starting with test-safe-outputs-custom-engine/ when testing pull request creation functionality. These branches were not being cleaned up by the existing test cleaner workflow, which only handled:

• Issues with prefix "[Custom Engine Test]"
• Pull requests with prefix "[Custom Engine Test]"
• Discussions with prefix "[Custom Engine Test]"

Solution

Extended the test cleaner workflow to also delete branches matching the pattern test-safe-outputs-custom-engine/*:

1. Added branch cleanup functionality - Uses GitHub REST API to list all repository branches and filters for those starting with the specified prefix
2. Updated permissions - Changed contents permission from read to write to allow branch deletion operations
3. Added error handling - Includes comprehensive error handling to ensure cleanup continues even if individual branch deletions fail
4. Maintained backward compatibility - All existing cleanup functionality remains unchanged

Technical Details

• Uses github.rest.repos.listBranches to retrieve all branches (paginated with 100 per page)
• Filters branches using JavaScript startsWith() method for the prefix test-safe-outputs-custom-engine/
• Deletes branches using github.rest.git.deleteRef with proper ref formatting (heads/${branchName})
• Provides console logging for monitoring cleanup operations
• Gracefully handles API errors and continues processing remaining branches

Testing

• Validated workflow syntax with actionlint
• Confirmed YAML syntax is valid
• All existing tests continue to pass
• Successfully ran make agent-finish validation suite

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• api.contoso.com
  • Triggering command: /tmp/go-build2776020575/b278/cli.test -test.testlogfile=/tmp/go-build2776020575/b278/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true (dns block)
  • Triggering command: /tmp/go-build3164563366/b278/cli.test -test.testlogfile=/tmp/go-build3164563366/b278/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true (dns block)
  • Triggering command: /tmp/go-build3834470846/b278/cli.test -test.testlogfile=/tmp/go-build3834470846/b278/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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