LU-16850 socklnd: remove ksnr_myiface from ksock_conn_cb

LU-16850 socklnd: remove ksnr_myiface from ksock_conn_cb

Drop ksnr_myiface: it is no longer needed since socklnd
TCP bonding got removed. There's one interface per
connection cb per peer_ni, and it can be accessed as
net->ksnn_interface.ksni_index.

Fix setting of ksni_nroutes accordingly. Duplication of
interface index in conn_cb and ksnn_interface was causing
the assertion
	ASSERTION( net->ksnn_interface.ksni_nroutes == 0 )
in ksocknal_shutdown() to fail if the corresponding
device is deregistered before lnd shutdown.

Modify test_214 of sanity-lnet to create connections so that
the scenario of socklnd shutdown with NI on a deregistered
interface is covered.

Lustre-change: https://review.whamcloud.com/51148
Lustre-commit: f6be07c457385cfacd9b802e4cade9f6f6ab7d6f

Fixes: a7ee03d7ca4185 ("LU-16378 lnet: handles unregister/register events)
Test-Parameters: trivial
Signed-off-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Change-Id: I4de164c9e64aa770164a8320b9460fadce49aa06
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51326
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Cyril Bordage <cbordage@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>