fix(gcloud): source `path.zsh.inc` always (#11901)

plugins/gcloud/gcloud.plugin.zsh

@@ -29,12 +29,10 @@ if [[ -z "${CLOUDSDK_HOME}" ]]; then
 fi
 
 if (( ${+CLOUDSDK_HOME} )); then
-  # Only source this if gcloud isn't already on the path
-  if (( ! $+commands[gcloud] )); then
+  # Source path file
   if [[ -f "${CLOUDSDK_HOME}/path.zsh.inc" ]]; then
     source "${CLOUDSDK_HOME}/path.zsh.inc"
   fi
-  fi
 
   # Look for completion file in different paths
   for comp_file (