replicainstall: add context manager for rpc client
    
    Abstract creating rpc client into a context manager to allow re-use.
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>