LU-15572 util: mirror delete with old MDS

LU-15572 util: mirror delete with old MDS

old MDS does not support mirror delete without volatile file and
clobbers the intent close error as -EBUSY, this patch catch the
ambiguous error and try the mirror delete using old way.

Fixes: b2d73351e6 ("LU-14521 flr: delete mirror without volatile file")
Test-Parameters: trivial
Test-Parameters: serverversion=2.14.0 testlist=sanity env=ONLY="0 50 60 61 203"
Test-Parameters: clientversion=2.14.0 testlist=sanity env=ONLY="0 50 60 61 203"
Test-Parameters: serverversion=2.12.8 testlist=sanity env=ONLY="0 50 60 61 203" serverdistro=el7.9
Test-Parameters: clientversion=2.12.8 testlist=sanity env=ONLY="0 50 60 61 203"
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: I497118cbb7da871268f0fdd6bdb88ad6bd831a26
Reviewed-on: https://review.whamcloud.com/46614
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>