LU-10395 tests: add test_280 sanity

LU-10395 tests: add test_280 sanity

The test reproduce a race between client llog processing
and MGS umount.

osd_fid2oi()) ASSERTION( osd->od_oi_table != NULL &&
osd->od_oi_count >= 1 ) failed: [0xa:0xb:0x0]

 #3 lbug_with_loc at ffffffffc0c098cb [libcfs]
 #4 __osd_oi_lookup at ffffffffc13e5610 [osd_ldiskfs]
 #5 osd_oi_lookup at ffffffffc13e76fd [osd_ldiskfs]
 #6 osd_fid_lookup at ffffffffc13e2cc5 [osd_ldiskfs]
 #7 osd_object_init at ffffffffc13e44e1 [osd_ldiskfs]
 #8 lu_object_start at ffffffffc0e262ab [obdclass]
 #9 lu_object_find_at at ffffffffc0e2a121 [obdclass]
 #10 dt_locate_at at ffffffffc0e2b6dd [obdclass]
 #11 llog_osd_open at ffffffffc0deae9e [obdclass]
 #12 llog_open at ffffffffc0dd8f3a [obdclass]
 #13 llog_origin_handle_next_block at  ffffffffc1200a06[ptlrpc]
 #14 tgt_llog_next_block at ffffffffc124b6c3 [ptlrpc]

Cray-bug-id: LUS-8505
Test-Parameters: standalonemgs=false trivial testlist=sanity envdefinitions=ONLY=280,ONLY_REPEAT=5
Signed-off-by: Alexander Boyko <c17825@cray.com>
Change-Id: I449b18779bfe391784ad532451213d5d5456c1b1
Reviewed-on: https://review.whamcloud.com/37635
Reviewed-by: Alexey Lyashkov <alexey.lyashkov@hpe.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>