LU-16434 tests: replace '-m' with '-i' in sanity/230j

LU-16434 tests: replace '-m' with '-i' in sanity/230j

In lfs_setdirstripe(), '-m' was originally used for '--mode'.
Fix sanity test_230j to replace '-m 0' with '-i 0' to force
directory creation on MDT0000 as the test expected.

Test-Parameters: trivial mdscount=2 mdtcount=4 \
env=ONLY=230j testlist=sanity

Change-Id: I10d435719f4b29ec47fa06c478caee9fcc8134a5
Fixes: 8deea7888c ("LU-11508 mdt: reject DoM file migration")
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49523
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>