ci: stop persisting credentials in google auth steps (#916)

Stop persisting credentials in direct wif

Author: dsotirakis

actions/login-to-gar/action.yaml

@@ -52,6 +52,7 @@ runs:
       with:
         project_id: "grafanalabs-workload-identity"
         workload_identity_provider: "projects/304398677251/locations/global/workloadIdentityPools/github/providers/github-provider"
+        create_credentials_file: false
     - name: Login to GAR
       if: ${{ steps.auth_with_service_account.outputs.access_token == '' }}
       uses: docker/login-action@74a5d142397b4f367a81961eba4e8cd7edddf772 # v3.4.0