Moved tests from browsertests repository to CirrusSearch repository

See also commits in browsertests[1] and CirrusSearch[2] repositories.

1: https://gerrit.wikimedia.org/r/#/c/113115/
2: https://gerrit.wikimedia.org/r/#/c/113131/

Bug: 61311
Change-Id: If9dfc4d10beb7bece81fdb77d6abea10f01e483e