nfs-proxy: kill mover on close

kill the mover on close if we did not have an
established data connection yet.

kill mover if we have failed to get a redirect within a
defined time window

Acked-by: Gerd Behrmann
Target: master, 2.11, 2.10, 2.9, 2.8, 2.7, 2.6
Require-book: no
Require-notes: no