Back out or modify patches for Mozilla's bug 1574980

The patches for bug 1574980 fix a security flaw in dealing with the maintenance service on Windows. We don't use that one, so we should be not affected. However, the way the fix was written is that it drags maintenance service related code into the general updater code: we build that now, too, which was not the case before. We don't want and need that and should either back out the whole patches (both for esr60 and esr68) or come up with a better solution.

I guess due to time constraints we follow the former idea and try to write better patches later on (and get those upstreamed).