fix(github): Clean up orphaned draft releases on publish failure

[BYK]

Summary

When a publish action fails (due to error or timeout) after creating a draft release, the draft is left orphaned on GitHub. This causes multiple draft releases with the same tag name to accumulate when someone re-runs the release.

Changes

• Add deleteRelease method to GitHubTarget that safely deletes draft releases
• The method refuses to delete non-draft releases as a safety measure
• Wrap the publish flow in try-catch to clean up drafts on failure
• Apply the same cleanup pattern to the UPM target
• Add tests for draft release cleanup behavior

Testing

• Added 4 new tests for deleteRelease method (draft check, non-draft refusal, undefined handling, dry-run)
• Added 4 tests for publish cleanup behavior (publishRelease failure, deleteRelease failure, success case, uploadAsset failure)
• All 641 tests pass

Fixes #388

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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Bug Fixes 🐛

• (github) Clean up orphaned draft releases on publish failure by @BYK in #681

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[Lms24]

nice!

[aldy505]

@BYK how do I use this? Self-hosted has lots of open orphan issues, the latest one is getsentry/publish#6794

[BYK]

@aldy505 this is only for draft releases during a GitHub publish action. We need to clean up stale publish issues ourselves. I'll go over them and close as there are many old issues that are still open.