reduce /gcbrun skip time

[DavidKorczynski]

When we dont need a trial run for a PR we use /gcbrun skip. However, there is still a lot of processing time for this workflow. We should reduce this.

[KKSurendran06]

Hi @DavidKorczynski

I looked into this issue and noticed that /gcbrun skip does not currently prevent all processing. Specifically:

There are no checks for /gcbrun skip in pypresubmit.yaml or in the helper/ scripts (presubmit and py_presubmit.py).

To address this, I’m considering two possible fixes:

1. Modify pypresubmit.yaml to completely skip the job if /gcbrun skip is in the PR body:
   if: "!contains(github.event.pull_request.body, '/gcbrun skip')"

2)Modify py_presubmit.py to exit early if /gcbrun skip is detected in the PR message:

pr_message = subprocess.check_output(['git', 'log', '-1', '--pretty=%B']).decode()
if "/gcbrun skip" in pr_message:
    print("Skipping Python presubmit checks due to /gcbrun skip")
    return 0 

Would this be the correct approach? Or should only specific parts of the process be skipped rather than the entire presubmit check?

I’d love to contribute a PR for this, any guidance would be greatly appreciated

Thanks!