Moved tests from browsertests repository

See also the commit[1] that deletes the tests from browsertests
repository and the commit[2] in mediawiki/selenium repository that
documents changes in Jenkins jobs.

1: https://gerrit.wikimedia.org/r/#/c/113101/
2: https://gerrit.wikimedia.org/r/#/c/113107/
3: https://bugzilla.wikimedia.org/show_bug.cgi?id=49313#c2

Bug: 61135
Change-Id: Ia4e812db3c6f8a46329fc4dc4b2b64f725a2d098
Merge "Moved tests from browsertests repository"