chore: update .repo-metadata.json (#210)

Author: parthea

packages/google-cloud-build/.repo-metadata.json

@@ -4,13 +4,14 @@
     "product_documentation": "https://cloud.google.com/cloud-build/docs/",
     "client_documentation": "https://cloud.google.com/python/docs/reference/cloudbuild/latest",
     "issue_tracker": "https://issuetracker.google.com/savedsearches/5226584",
-    "release_level": "ga",
+    "release_level": "stable",
     "language": "python",
     "library_type": "GAPIC_AUTO",
     "repo": "googleapis/python-cloudbuild",
     "distribution_name": "google-cloud-build",
     "api_id": "cloudbuild.googleapis.com",
     "codeowner_team": "@googleapis/cicd",
     "requires_billing": false,
-    "default_version": "v1"
+    "default_version": "v1",
+    "api_shortname": "cloudbuild"
 }