LU-14361 tests: add aheadmany to .gitignore

LU-14361 tests: add aheadmany to .gitignore

Add aheadmany to .gitignore.

Fixes: 5317f8a ("LU-14361 statahead: Add test for statahead advise")
Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I1003200b7ed34e90d2aa0f75cb4c4f071eaeea04
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53173
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: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>