Change cloudbuild image (#5448)

Changes the image to the more generic option.

cloud_build/stage.yaml

@@ -10,7 +10,7 @@ steps:
 
         echo "Building the website using a makefile..."
         make build
-  - name: gcr.io/flutter-dev-230821/firebase-staging
+  - name: gcr.io/flutter-dev-230821/firebase-ghcli
     entrypoint: '/bin/bash'
     args:
       - '-c'