LU-14930 mdt: abort_recov_mdt shouldn't abort client recovery

LU-14930 mdt: abort_recov_mdt shouldn't abort client recovery

When abort_recov_mdt is set to abort MDT-MDT recovery then
abort_recovery flag is set too inside target_stop_recovery_thread()
call, that causes not just MDT-MDT recovery abort but aborts
also clients/MDT recovery.

Fixes: dd9e79b64d ("LU-12546 mdt: abort recovery between MDTs")
Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: Ibda05e91a2da90156e2b6c9fdcb2169cdbd50fe4
Reviewed-on: https://review.whamcloud.com/44610
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>