LU-15847 tgt: reply always with the latest assigned transno

LU-15847 tgt: reply always with the latest assigned transno

In tgt_txn_stop_cb() don't skip transno assignment in case
of unexpected multiple last_rcvd updates. So the latest
transno will be reported back in reply but not the first
one.

The reporting of just the first transno might lead to data
loss at failover because partially committed operation will
be considered as fully committed and rest of operation will
not be replayed.

Proposed way with reporting the last assigned transno to
the client could cause replay failures in some cases which
is still better that possible data loss. So patch makes a
multiple transaction case less severe.

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: Ia07e89576127a2fc1eb2ae706551ffe8ceaa93be
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/47492
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>