fix(discord): log an unexpected liveness-probe exit at WARNING (from #118504)

The guard exit in _liveness_loop fires for two very different reasons:
ordinary teardown (adapter stopped or disconnecting), and a still-running
adapter whose client vanished. The first is noise at INFO; the second
means the gateway keeps running with no watchdog (#118487) and must stand
out in an incident log. Pick the level from the exit cause instead of
logging both at INFO.

Co-authored-by: Konstantin Khlopkov <47825603+kokhlo@users.noreply.github.com>

plugins/platforms/discord/adapter.py

@@ -1754,8 +1754,12 @@ class DiscordAdapter(DiscordMediaMixin, BasePlatformAdapter):
             client = self._client
             if not self._running or client is None or self._disconnecting:
                 # The probe must never disappear silently (#118487): an exit here leaves the
-                # gateway alive with no watchdog, so say why before going away.
-                logger.info(
+                # gateway alive with no watchdog, so say why before going away. Teardown
+                # (stopped or disconnecting) is expected; a still-running adapter losing
+                # its client mid-flight is not, and an operator must be able to spot it.
+                expected_exit = not self._running or self._disconnecting
+                logger.log(
+                    logging.INFO if expected_exit else logging.WARNING,
                     "[%s] Discord liveness probe exiting (running=%s, client=%s, disconnecting=%s)",
                     self.name, self._running, client is not None, self._disconnecting,
                 )