core (xmpp): Cache unreachable server on presence error to avoid disco queries:

In case of dead server/component with lot of contacts, we may receive a lot of
`<presence>` error with `remote-server-not-found` conditions. This patch use this to mark
the server as unreachable and avoid to do disco queries there.

libervia/backend/core/xmpp.py

@@ -2268,6 +2268,25 @@ class SatPresenceProtocol(xmppim.PresenceClientProtocol):
             entity, C.PRESENCE_UNAVAILABLE, 0, statuses, self.parent.profile
         )
 
+    def errorReceived(self, presence):
+        """Handle error presence.
+
+        Cache unreachable servers to avoid future disco queries.
+        """
+        try:
+            e = error.exceptionFromStanza(presence)
+            assert isinstance(e, error.StanzaError)
+            if e.condition == "remote-server-not-found":
+                from_jid = jid.JID(presence["from"])
+                server_jid = jid.JID(from_jid.host)
+                self.host.memory.disco._jid_disco_cache[server_jid] = (None, time.time())
+                log.debug(
+                    f"Server {server_jid} marked as unreachable from "
+                    "presence error"
+                )
+        except Exception:
+            log.exception("Can't handle presence error")
+
     def available(self, entity=None, show=None, statuses=None, priority=None):
         """Set a presence and statuses.