build: configure google-cloud-go for automated generation (#1839)

Fixes #1666

Signed-off-by: Jeff Ching <chingor@google.com>

Author: chingor13

internal/automation/prod/repositories.yaml

@@ -6,3 +6,10 @@ repositories:
       - generate
       - stage-release
       - publish-release
+  - name: "google-cloud-go"
+    full-name: https://github.com/googleapis/google-cloud-go
+    github-token-secret-name: "google-cloud-go-github-token"
+    supported-commands:
+      - generate
+      - stage-release
+      - publish-release