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/swarm/test_swarm_api.py

@@ -464,7 +464,7 @@ def test_list_deckies_joins_host_identity(client: TestClient, repo) -> None:
             "services": ["smb", "ssh"], "state": "failed", "last_error": "boom",
         })
 
-    asyncio.get_event_loop().run_until_complete(_seed())
+    asyncio.run(_seed())
 
     rows = client.get("/swarm/deckies").json()
     assert len(rows) == 2