spec: stub google docs config, instead of relying on PluginSetting

Change-Id: I260a785db3a1fd0b40e9c5904287be1437515554
Reviewed-on: https://gerrit.instructure.com/28734
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: James Williams  <jamesw@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>