Revert "Update translation pages on deleting translation unit"

This reverts commit 939459cc3c80b12e3f95f05e4e9ecf6f6b35805f.

Causes PHP Fatal error:  Call to undefined method FileBasedMessageGroup::getTitle() in
/www/translatewiki.net/w/extensions/Translate/tag/PageTranslationHooks.php on line 929

Change-Id: I94eb2370d3d0f7cb0d472893e0cfeade84d8d3fc
Merge "Revert "Update translation pages on deleting translation unit""