LU-14697 tests: change performance-sanity to use mdtest

LU-14697 tests: change performance-sanity to use mdtest

Replace mdsrate by mdtest in performance-sanity.sh

Test-Parameters: trivial
Test-Parameters: testlist=performance-sanity clientdistro=el7.9
Test-Parameters: testlist=performance-sanity clientdistro=el8.8
Test-Parameters: testlist=performance-sanity clientdistro=el9.2
Test-Parameters: testlist=performance-sanity clientdistro=ubuntu2204
Signed-off-by: Alex Deiter <adeiter@tintri.com>
Change-Id: I1a80bab4ccbe085d3ff8d8b332c8e117e14ea9cb
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51414
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>