Update the autonym for aeb in Names.php

The new name was suggested by Wikimedia's Language committee,
and as far as I know Arabic, it looks correct to me as well.

A Latin script autonym is being discussed separately and will be
added if and when there will be a decision about it.

The Arabic script autonym should be changed already now
because the current one is definitely wrong.

See also https://github.com/wikimedia/jquery.uls/pull/167 .

Change-Id: Ib07d2b49a47fb7f349a2cd70b7acfd88f9bf66ca