LU-14361 statahead: wait inuse entry finished during cleanup

LU-14361 statahead: wait inuse entry finished during cleanup

If the entry is being used by the user process when the statahead is
doing cleanup and quit, it must wait for the inuse entry finished
and then kill the local cached entries in statahead context.

Add sanity/test_123{k,l} to verify it.

Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I747badd85bd44cb20f7d37ca3126ca308a632371
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49291
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>