LU-17276 tests: performance test case for flock

LU-17276 tests: performance test case for flock

Add some test cases for flock performance.

Test-Parameters: trivial testlist=performance-sanity env=ONLY=6,ONLY_REPEAT=50
Signed-off-by: Yang Sheng <ys@whamcloud.com>
Change-Id: Id76d38e14bec6a095fe26e22d08569731d4669c9
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53558
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Deiter <alex.deiter@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>