Fix NameError in build_and_push_test_images.py (#14470)

Resolved a `NameError` in
`infra/build/functions/build_and_push_test_images.py` by defining the
missing `logs_url` variable. This ensures that build failures are
reported correctly with a link to the logs, instead of crashing the
script.

---
*PR created automatically by Jules for task
[7867762740301415816](https://jules.google.com/task/7867762740301415816)
started by @hunsche*

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: Matheus Aoki Hunsche <[email protected]>

Author: google-labs-jules[bot]

infra/build/functions/build_and_push_test_images.py

@@ -96,6 +96,7 @@ def _run_cloudbuild(build_body):
 
 def wait_for_build_and_report_summary(build_id, cloud_project='oss-fuzz-base'):
   """Waits for a GCB build to complete and reports a detailed summary."""
+  logs_url = build_lib.get_logs_url(build_id)
   credentials, _ = google.auth.default()
   cloudbuild = cloud_build('cloudbuild',
                            'v1',