LU-16838 tests: use import name in 398a

LU-16838 tests: use import name in 398a

The LU-15670 test change assumes ost1_import is always
OST0000.  This isn't quite always true, so the test is
failing in certain configurations.

Change it to use the import name.

Lustre-change: https://review.whamcloud.com/51064
Lustre-commit: TBD (from 1927445073bc49c0941e72528590f626b80e9c8f)

Fixes: 649d638467 ("LU-15670 clio: Disable lockless for DIO with O_APPEND")
Test-parameters: trivial
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Ifaefc503d1118ecd6fd45b661cbe94607f7ad799
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52287
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>