s3:dbwrap_ctdb: improve the error handling in ctdb_async_ctx_init_internal()

We should not map any error from ctdbd_init_async_connection() to EIO.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Jul  1 18:34:17 UTC 2022 on sn-devel-184