feat(gcloud): support macports installation path (#11133)

Closes #11133

plugins/gcloud/gcloud.plugin.zsh

@@ -13,6 +13,7 @@ if [[ -z "${CLOUDSDK_HOME}" ]]; then
     "/usr/lib/google-cloud-sdk"
     "/usr/lib64/google-cloud-sdk"
     "/opt/google-cloud-sdk"
+    "/opt/local/libexec/google-cloud-sdk"
   )
 
   for gcloud_sdk_location in $search_locations; do