fix(mount): don't release file handles from Forget
Forget(nodeid, nlookup) only decrements the kernel inode lookup count.
File handle lifecycle belongs to FUSE Open/Release. Driving the FH
refcount from Forget coupled two unrelated counters and could tear down
a still-live handle if Forget ever raced ahead of Release.
Drop the ReleaseByInode call (and the now-unused method).