LU-17426 tests: add crossdir parallel rename test

LU-17426 tests: add crossdir parallel rename test

Add sanityn test_81d to test cross-dir (same-MDT) parallel rename
if the MDT supports this functionality.

Lustre-change: https://review.whamcloud.com/47643
Lustre-commit: TBD (from fdd1f9df934efa070cd4aca4cf3db686261ef868)

Test-Parameters: trivial testlist=sanityn
Test-Parameters: testlist=sanityn serverversion=2.15
Test-Parameters: testlist=sanityn env=ONLY=81d,ONLY_REPEAT=10
Test-Parameters: testlist=sanityn env=ONLY=81d,ONLY_REPEAT=10 mdtcount=2
Test-Parameters: testlist=sanityn env=ONLY=81d,ONLY_REPEAT=10 mdtcount=4
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ic8717e6865a9c6c9698186f4fdf34c1f4f74083f
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53748
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>