Drop Contractor #836
Description
According to elementary/calendar#908, pre-installed system apps (like Calendar, Photos, Code) are being migrated to Granite Share and/or XDG portals. Therefore, Contractor support should be removed (again, this is indicated in elementary/calendar#908).
Note: The topic of Contractor's presence in the project has also been discussed previously, and as an additional link, I can attach the discussion issue: elementary/contractor#1 (this is what I personally saw)