They are not valid anymore since the Iuh conn is closed.
If kept alive, then if GTP/RTP traffic comes from CN while shutting down
the payloads may be forwarded to LLSK which may have been closed (eg.
because shutdown procedure was started precisely due to death LLSK
because other end closed it).
Related: OS#6826
Change-Id: I51aa449e7fd5b1049fcaaeef3f1378423a838c05