fix(tests): align stale tests with current behavior

- swarm/test_swarm_api, swarm/test_heartbeat: replace deprecated
  asyncio.get_event_loop().run_until_complete() with asyncio.run();
  the former raises in 3.11 once another test has set+closed a loop on
  the main thread.
- prober/test_prober_bus, prober/test_prober_worker: extend tcp_fingerprint
  mocks with tos/dscp/ecn/server_isn so the worker doesn't KeyError into
  the prober_error branch.
- services/test_service_isolation: collector now retries on event-stream
  errors instead of exiting; assert it stays running and cancel cleanly.
- live/test_imap_live, live/test_pop3_live: log format emits
  outcome="failure", not "failed".
- live/test_service_isolation_live: is_service_container accepts label
  OR state-name; rewrite the empty-state test against a synthetic
  unlabeled container instead of the host's real fleet.

tests/services/test_service_isolation.py

@@ -16,6 +16,7 @@ worker degrades gracefully while unrelated workers remain unaffected.
 """
 
 import asyncio
+import contextlib
 import json
 import os
 import time
@@ -68,8 +69,12 @@ class TestCollectorIsolation:
             with patch("decnet.config.load_state", return_value=None):
                 task = asyncio.create_task(log_collector_worker("/tmp/decnet-test-collector.log"))
                 await asyncio.sleep(0.1)
-                assert task.done()
-                assert task.exception() is None
+                # Collector now retries on event-stream errors instead of
+                # exiting; it should still be running (i.e. surviving) here.
+                assert not task.done()
+                task.cancel()
+                with contextlib.suppress(asyncio.CancelledError):
+                    await task
 
     def test_collector_container_filter_with_unknown_containers(self):
         """is_service_container must reject containers not in state."""