LU-11085 tests: add a test case for same range lock

LU-11085 tests: add a test case for same range lock

Add a new case in ldlm_extent to test performance for
same range work with interval tree.

Signed-off-by: Yang Sheng <ys@whamcloud.com>
Change-Id: Ia3ffe90263a2a7f01a3a44f8801a32fc789b5abc
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54565
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>