s4:rpc_server/remote: defer the connect to the first client request

s4:rpc_server/remote: defer the connect to the first client request

This means we have a chance to use delegated credentials from the client
if available, as the authentication is already completed.

Before we only ever used the transport inherited credentials
via SMB or anonymous.

Note: most times we still fallback to anonymous...

BUG: https://bugzilla.samba.org/show_bug.cgi?id=7113
BUG: https://bugzilla.samba.org/show_bug.cgi?id=11892

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>