Make tests that wait for concurrent work wait on the event or a condition with a long deadline (issue 1814)

A test that slept a fixed time and then asserted what a goroutine, process or
watcher did failed under the checker's load. Each now waits for its positive
evidence (a started baseline, a call counted, a state reached) within 30 s, and
the concurrency-limit tests meet at a barrier instead of overlapping by sleep.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

modules/mesh-knowledge/cmd/mesh-knowledge/bus_test.go

@@ -380,7 +380,7 @@ func TestTheKnowledgeBaseOverTheBus(t *testing.T) {
 		t.Fatalf("history: %+v", h)
 	}
 	// Every change said on the bus, as the module, with who acted.
-	deadline := time.Now().Add(5 * time.Second)
+	deadline := time.Now().Add(30 * time.Second)
 	for time.Now().Before(deadline) && len(w.of(EventProposed)) == 0 {
 		time.Sleep(50 * time.Millisecond)
 	}

modules/mesh-knowledge/cmd/mesh-knowledge/caller_test.go

@@ -46,7 +46,7 @@ func whoCalled(t *testing.T, params map[string]any) string {
 	select {
 	case who := <-got:
 		return who
-	case <-time.After(3 * time.Second):
+	case <-time.After(30 * time.Second):
 		t.Fatal("the call was not answered")
 		return ""
 	}