Setup test.wikidata as repo for test2 and test.wikipedia

test2 allows running qunit tests, which has unintended
side-effects (creating ghost items on wikidata).

making test2 the primary test client for testing page moves.

removing test2 from the wikidataclient.dblist. test2wiki has
wikibase client enabled via $wmgUseWikibaseClient = true in
InitialiseSettings.php

these changes result in test2 not getting change propagations,
which can be fixed by adding another cronjob and/or
making the ChangeNotification jobs work via jobqueue / redis.

Bug: 61893
Change-Id: I6f4c512e0b37f49e0446c9b92ce3bcf0dc33a9de