Move validateAllAlias code into separate class

This has a minor change in functionality:

It contains code from removeOldIndeciesIfRequired already, while that's
also still in the maintenance script. Goal is for validateSpecificAlias
to also move into a Validator class, that extends from this new
Validator class.
In maintenance script, both (AllAlias & SpecificAlias) were run, and
stuff in $this->removeIndecies was cleaned up after both were run. If
we move both into separate objects, the $this->removeIndecies alternative
will be run twice, right after each has run.

Change-Id: Idbbd403b8190ae832a6b15734adb25b71d43b534