UC-83 Remove the unecessary UserLoadFromSession hook

This hook was created to allow the FBConnect 3rd party extension to add Facebook connect functionality to Wikia.  It uses complex logic to determine whether the user intends to connect their Wikia account to FB.  FB connectivity is core to the social experience at Wikia and is being brought in as Wikia owned code rather than a 3rd party extension.  This PR eliminates heuristic logic and replaces with direct intent; the user is sent where they need to go without any redirects.

https://wikia-inc.atlassian.net/browse/UC-83