Checkout base branch instead of PR head in build workflow

[Pearl1594]

No description provided.

[yadvr]

I think without this, gha won't run for PRs from forks. Need to double check cc @Pearl1594@shwstppr@DaanHoogland@vishesh92

[Pearl1594]

Seems to work on forks @yadvr; Raised a PR from my fork to this PR and the gha ran: #205

[Copilot]

Pull request overview

This PR refactors the PR build/comment flow by moving PR commenting into a separate workflow_run workflow and switching the build workflow to run on pull_request rather than pull_request_target.

Changes:

• Add a new workflow_run workflow to comment/update PR build results after the build completes.
• Change the build workflow trigger from pull_request_target to pull_request and simplify checkout configuration.
• Remove the in-workflow PR commenting job from the build workflow.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
.github/workflows/comment-pr-build.yml	New workflow that posts/updates a PR comment based on the completed build workflow run.
.github/workflows/build-pr-cmk.yml	Switch build trigger to pull_request, adjust checkout, and remove the inline commenting job.

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[Copilot]

The PR title indicates the build should check out the base branch, but with on: pull_request and no explicit ref, actions/checkout will check out the PR merge ref (refs/pull/<n>/merge) by default (i.e., merged PR tip, not base). If the intention is truly to build the base branch, set ref to the base ref/SHA; otherwise the PR title/description should be updated to match the behavior.

[github-actions]

❌ Build failed for PR #204.

See the run: https://github.com/apache/cloudstack-cloudmonkey/actions/runs/22101054048