test(#606): native-ack routing waits for the driver child to be Connected; widen a starved poll

DriverHostActorNativeAlarmAckRoutingTests: Applied does not mean the child DriverInstanceActor is
Connected, and an ack reaching a still-Connecting child is dropped by design — the single
positive-control ack was itself dropped (4/20 under DOTNET_PROCESSOR_COUNT=1 x8, still failing
with the presence budget dilated to 45 s, so not a budget problem). SpawnHostAndApply now waits
for SubscribeAlarmsAsync, which only the Connected state calls. ScriptedAlarmEngine
OnEvent_emission_happens_outside_evalGate: 2 s blocking poll -> 15 s (5/20 under starvation).

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

tests/Core/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/ScriptedAlarmEngineTests.cs

@@ -769,8 +769,11 @@ public sealed class ScriptedAlarmEngineTests
             // Drive to Active so Acknowledge has something to ack.
             up.Push("Temp", 150);
             // Use the same WaitForAsync that other tests use — synchronously
-            // here since this is a non-async test.
-            for (var i = 0; i < 80 && eng.GetState("HighTemp")!.Active != AlarmActiveState.Active; i++)
+            // here since this is a non-async test. A 15 s presence ceiling, not 2 s: this thread blocks a
+            // pool thread while the drain that activates the alarm needs another, and under thread-pool
+            // starvation (DOTNET_PROCESSOR_COUNT=1, 8 parallel copies) 2 s failed 5 runs in 20 (#606).
+            var activeBy = DateTime.UtcNow.AddSeconds(15);
+            while (DateTime.UtcNow < activeBy && eng.GetState("HighTemp")!.Active != AlarmActiveState.Active)
                 Thread.Sleep(25);
             eng.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Active);