remove supportUnlocked check that is not worth its overhead

remove supportUnlocked check that is not worth its overhead

moveAnnex only gets to that check if the object file was not present
before. So in the case where dup files are being added repeatedly,
it will only run the first time, and so there's no significant speedup
from doing it; all it avoids is a single sqlite lookup. Since MVar
accesses do have overhead, it's better to optimise for the common case,
where unlocked files are supported.

removeAnnex is less clear cut, but I think mostly is skipped running on
keys when the object has already been dropped, so similar reasoning
applies.