Cleanup: mobile search feature moved to MobileFrontent repository

For more information see:
https://gerrit.wikimedia.org/r/#/c/39771/
https://gerrit.wikimedia.org/r/#/c/39773/

Change-Id: I1ec63e87c8758b97975ac7fbc10f7c22cf254559
Merge "Cleanup: mobile search feature moved to MobileFrontent repository"