sideband: mark "remote error:" prefix for translation

sideband: mark "remote error:" prefix for translation

A Git client may produce a "remote error:" message (along with whatever
error the other side sent us) in two places:

  - when we see an ERR packet

  - when we're using a sideband and see sideband 3

We can't reliably translate the message the other side sent us, but we
can do so for our own prefix. However, we translate only the ERR-packet
case but not the sideband-3 case. Let's make them consistent (by marking
both for translation).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>