nfs: stop embedded portmap on shutdown

Ticket: #8551
Acked-by: Gerd Behrmann
Target: master, 2.11, 2.10
Require-book: no
Require-notes: no
(cherry picked from commit e359c62877f82319945c91dd4bc6ea4aa096484a)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>