Remove Cloud Run deploy bootstrap commands

[anth-volk]

Fixes #3657

Summary

• Remove gcloud services enable from the Cloud Run image build script.
• Remove Artifact Registry repository auto-creation from the deploy path.
• Fail clearly if the expected Artifact Registry repository is missing.

Verification

• bash -n .github/scripts/build_cloud_run_image.sh
• CLOUD_RUN_DRY_RUN=1 GITHUB_SHA=1234567890abcdef GITHUB_RUN_NUMBER=42 bash .github/scripts/build_cloud_run_image.sh

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.98%. Comparing base (cf629b5) to head (84d1a0f).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3658   +/-   ##
=======================================
  Coverage   78.98%   78.98%           
=======================================
  Files          72       72           
  Lines        4269     4269           
  Branches      790      790           
=======================================
  Hits         3372     3372           
  Misses        693      693           
  Partials      204      204           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.