Moved the last two MobileFrontend jobs from Cloudbees

Created jobs:

browsertests-MobileFrontend-en.m.wikipedia.org-linux-firefox-sauce
browsertests-MobileFrontend-test2.m.wikipedia.org-linux-firefox-sauce

Paired with: Chris McMahon

Change-Id: I194973896b50f7b7786ab10adf9f7d0c62e8e965