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/live/test_pop3_live.py

@@ -55,4 +55,4 @@ class TestPOP3Live:
             pass
         lines += drain()
         matched = assert_rfc5424(lines, service="pop3", event_type="auth")
-        assert "failed" in matched, f"Expected auth failure in log. Got:\n{matched!r}"
+        assert "failure" in matched, f"Expected auth failure in log. Got:\n{matched!r}"