[vfs2] Destroy all tmpfs files when the filesystem is released.
[vfs2] Destroy all tmpfs files when the filesystem is released.

In addition to fixing reference leaks, this change also releases memory used
by regular tmpfs files once the containing filesystem is released.

PiperOrigin-RevId: 336833111

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor