chore(docs): remove unused gruntUtils import from docs config

As of commit 11c5bb7, the gruntUtils import is no longer needed in the
gitData docs config service.

Closes #9446

docs/config/services/gitData.js

@@ -1,6 +1,5 @@
 "use strict";
 
-var gruntUtils = require('../../../lib/grunt/utils');
 var versionInfo = require('../../../lib/versions/version-info');
 
 /**