LU-15816 tests: use correct ost host to manage failure

LU-15816 tests: use correct ost host to manage failure

sanity test_398m sets up striping across 2 OSTs.  It ensures that
failing IO to either OST individually will fail the total IO.

However it sends the command to fail IO for the second OST (OST1) to
the host managing the first OST (ost1).  If the first 2 OSTs are on
the same host, this works.  If not, it fails.

Also there error messages when testing the second stripe say "first
stripe".

Test-Parameters: trivial env=ONLY=398m
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ic7085dab2610fa2c044a966fd8de40def0438ca4
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49248
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>