fix(gcloud): add support for `brew` installations (#11772)

plugins/gcloud/gcloud.plugin.zsh

@@ -6,6 +6,7 @@
 if [[ -z "${CLOUDSDK_HOME}" ]]; then
   search_locations=(
     "$HOME/google-cloud-sdk"
+    "/usr/local/share/google-cloud-sdk"
     "/usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk"
     "/opt/homebrew/Caskroom/google-cloud-sdk/latest/google-cloud-sdk"
     "/usr/share/google-cloud-sdk"