LU-16297 ptlrpc: don't panic during reconnection

LU-16297 ptlrpc: don't panic during reconnection

ptlrpc_send_rpc() could race with ptlrpc_connect_import_locked()
in the middle of assertion check and this leads to a wrong panic.
Assertion checks

(AT_OFF || imp->imp_state != LUSTRE_IMP_FULL ||

reconnect changes import state and flags
and second part

(imp->imp_msghdr_flags & MSGHDR_AT_SUPPORT) ||
!(imp->imp_connect_data.ocd_connect_flags & OBD_CONNECT_AT)))

MSGHDR_AT_SUPPORT is disabled during client reconnection.
It is not good to use locking at this hot part, so fix changes
assertion to a report.

HPE-bug-id: LUS-10985
Signed-off-by: Alexander Boyko <alexander.boyko@hpe.com>
Change-Id: Ifc9e413c679c3e8a4c8f4f541251bebabae41c82
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49029
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alexander Zarochentsev <alexander.zarochentsev@hpe.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>