Rework article moves

This:
* Prevents lots of actions from happening twice on article move
* Fixes a bug where if an article moved from one index to another it wouldn't
be removed from the first index
* Adds article being in the wrong index to the list of things saneitize.php
can catch.

Bug: 66670
Change-Id: Ia49838993fd51fda9cc487a4f157057fed24aa5d
Merge "Rework article moves"