Moved two browsertests-qa jobs to Sauce Labs

Created jobs:
browsertests-qa-en.wikipedia.beta.wmflabs.org-linux-firefox-sauce
browsertests-qa-test2.wikipedia.org-linux-firefox-sauce

Deleted jobs:
browsertests-qa-en.wikipedia.beta.wmflabs.org-linux-firefox
browsertests-qa-test2.wikipedia.org-linux-firefox

Paired with: Chris McMahon

Change-Id: I7c0d55e452e2f45b73cc579bd23ee1022460ba04