Fixed bug in ThanksLogModel::GetObjectInsertUserID()

* Method was not retrieving the correct InsertUserID for object type "question" (introduced by QnA plugin).
Fixed bugs in logic used to process thanks given to Discussions

* Fixed bug in ThanksLogModel::GetObjectInsertUserID(). Ref. https://app.asana.com/0/8217127514025/14847004046288.
* Fixed bug in ThankfulPeoplePlugin::Controller_GiveThanks(). Ref. https://app.asana.com/0/8217127514025/14847004046290