LU-14714 mgc: server to mount without local config

LU-14714 mgc: server to mount without local config

Server uses local config copy to mount with but
that is not the case always. Local config can be
damaged or empty and may be not updated from MGS,
e.g. due to -ENOSPC on server upon llog backup or
other errors. That causes empty or partial local
config so server unable to mount with it.

Patch allows a server to mount first from remote config
if local config wasn't copied from MGS. If remote
processing is not possible or failed then local config
is used as last attempt to mount.

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I442a4f20eeb7deb1b40ccc7cabb1fae65804e211
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55283
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>