fix: switch pgvector image build to SA key auth (bypass broken WIF)

.github/workflows/build-pgvector-image.yml

@@ -10,7 +10,6 @@ env:
 
 permissions:
   contents: read
-  id-token: write
 
 jobs:
   build:
@@ -22,8 +21,8 @@ jobs:
       - name: Authenticate to GCR
         uses: google-github-actions/auth@v2
         with:
-          workload_identity_provider: "projects/devops-lab-cluster/locations/global/workloadIdentityPools/github-pool/providers/github-provider"
-          service_account: "github-deployer@devops-lab-cluster.iam.gserviceaccount.com"
+          credentials_json: ${{ secrets.GCLOUD_SERVICE_ACCOUNT_KEY }}
+          project_id: devops-lab-cluster
           token_format: access_token
 
       - name: Docker Login to GCR