LU-17440 tests: Fix sanity-lnet/test_226

LU-17440 tests: Fix sanity-lnet/test_226

test_226 is not deleting a route from the remote peer as intended.
This is because of two issues. The first issue is that the wrong
gateway NID is being provided to do_route_del(). The second issue is
that do_route_del() is not correctly quoting the remote command to
detect and delete routes. The correct NID is now specified and
the quoting in do_route_del() has been fixed. Some additional
output was also added so that we can verify via test output that it is
working correctly.

Test-Parameters: trivial testlist=sanity-lnet
Fixes: 2b210f3905 ("LU-17440 lnet: prevent errorneous decref for asym route")
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: Ie21a1bdb174cb65ae64134a727d69e1c95a4ddd5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55397
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Gian-Carlo DeFazio <defazio1@llnl.gov>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>