LU-16551 tests: Ensure all peer credits used in MR

LU-16551 tests: Ensure all peer credits used in MR

sanity-lnet test_254 needs to ensure that all peer credits are
consumed. Because of the raciness of the round robin code in LNet,
we cannot rely on just issuing the appropriate number of pings.
Instead we should use the --source argument to lnetctl ping to ensure
that we send the correct number of pings over each interface.

To simplify matters, only perform this test, and the other tests that
call setup_health_test(), in non-routed configurations.

Lustre-change: https://review.whamcloud.com/49979
Lustre-commit: aa66cb46761d72ec2c861ff9665ea6b6dbbe76a8

Test-Parameters: trivial testlist=sanity-lnet
Fixes: 52db11cdce ("LU-16303 lnet: Drop LNet message if deadline exceeded")
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: I05a7ffec37d16c14711fe696232708f927357b1c
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51699
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Cyril Bordage <cbordage@whamcloud.com>