Remove triggerupdate

@DeepDiver1975 @PVince81 @icewind1991 I was digging through the file scan stuff and stumbled over triggerupdate.php, only later saw the junior jobs.

triggerupdate actually checks hasUpdated() before making the scan, so there is a difference in behavior between triggerupdate and `occ files:scan --path="foo/bar"`.

Anyway, leaving this here until someone decides what to do with it