Remove dead branch in ControllerMap::lookupDefaultController()

Remove dead branch in ControllerMap::lookupDefaultController()

It was impossible to take this branch since
d10487d5b8f54ce86fa8d8f36649febd338dbae8, because since this commit i18n CMS
pages (which this branch was about) were unable to have an empty custom URL.

Since 1bfaae39040d6b56ed837b5c66aa7931ffaca9b5 it is entirely impossible for
any empty custom URLs to exist, making this branch completely dead.

Further it only ever supported the WCF landing page, not any application's
landing pages.

The original intent of this branch will be restored in a follow up commit.