memory (disco): handle remote-server-timeout in get_infos errback:

`remote-server-timeout` is treated like `remote-server-not-found`.

libervia/backend/memory/disco.py

@@ -318,7 +318,10 @@ class Discovery:
                     fail = failure.Failure(exceptions.TimeOutError(str(fail.value)))
                 elif fail.check(StanzaError):
                     stanza_error = fail.value
-                    if stanza_error.condition == "remote-server-not-found":
+                    if stanza_error.condition in (
+                        "remote-server-not-found",
+                        "remote-server-timeout",
+                    ):
                         # Mark the server as unreachable (store as domain JID)
                         server_jid = jid.JID(jid_.host)
                         self._jid_disco_cache[server_jid] = (None, time.time())