fix(acs-ci): bound GCS preflight request

[robbycochran]

Use gsutil bucket metadata for the ACS preflight instead of enumerating the entire logs prefix. This keeps the connectivity check bounded while still exercising the sandbox CA bundle and GCS provider.

Summary by CodeRabbit

• Bug Fixes
  • Updated the nightly preflight check to verify that the configured storage bucket exists directly, improving validation accuracy.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between d951cac and 73003e7.

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• tasks/acs-ci-nightly/workflow/preflight.yaml

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Walkthrough

The GCS preflight check now validates bucket existence with gsutil ls -b gs://$GCS_BUCKET instead of listing the logs/ prefix. Pass/fail handling and status propagation remain unchanged.

Changes

GCS preflight validation

Layer / File(s)	Summary
Bucket existence check tasks/acs-ci-nightly/workflow/preflight.yaml	The workflow checks GCS bucket metadata with gsutil ls -b instead of listing the logs/ prefix. Existing pass/fail handling remains unchanged.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~3 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 73003

The preflight now validates bucket metadata without enumerating the logs prefix, with no merge-blocking risk identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: bounding the GCS preflight request in ACS CI.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[stackrox-openshell-workflow]

This check no longer verifies the existence of the logs subdirectory, only the bucket itself. This seems like a weaker preflight check that could allow subsequent steps to fail if they depend on that directory. Is this change intended?