Refactor how builder-api is restarted upon library sync

- redeploys the same image instead of relying on `:latest`
- adds a timestamp so we know that the sync happened and when

Author: prestoncabe

.github/workflows/load-library-metadata.yml

@@ -7,7 +7,6 @@ on:
 env:
   PROJECT_ID: benefit-decision-toolkit-play
   REGION: us-central1
-  SERVICE: benefit-decision-toolkit-play
   WORKLOAD_IDENTITY_PROVIDER: projects/1034049717668/locations/global/workloadIdentityPools/github-actions-google-cloud/providers/github
 
 jobs:
@@ -55,6 +54,6 @@ jobs:
 
       - name: Restart builder-api with updated library metadata
         run: |
-          gcloud run deploy builder-api \
-            --image us-central1-docker.pkg.dev/${{ env.PROJECT_ID }}/${{ env.SERVICE }}/builder-api:latest \
-            --region ${{ env.REGION }}
+          gcloud run services update builder-api \
+            --region ${{ env.REGION }} \
+            --update-env-vars LIBRARY_SYNC_TIMESTAMP=$(date -u +%Y%m%dT%H%M%SZ)