fix: ensure we cleanup the data directory on app deletion

Also use a variable for the clone root dir.

plugins/git/post-delete

@@ -7,8 +7,10 @@ trigger-git-post-delete() {
   declare desc="destroys the git properties for a given app"
   declare trigger="post-delete"
   declare APP="$1"
+  local APP_CLONE_ROOT="$DOKKU_LIB_ROOT/data/git/$APP"
 
   fn-plugin-property-destroy "git" "$APP"
+  rm -rf "$APP_CLONE_ROOT"
 }
 
 trigger-git-post-delete "$@"