CommissioningWindowManager should only listen for platform events whe…

…n a commissioning window is open. (#28311)

Right now, a CommissioningWindowManager starts listening for platform events if
a commissioning window is opened, and then never stops.  That means it can end
up reacting to fail-safe expirations that have nothing to do with a
commissioning window (e.g. CASE updates of state that needs a fail-safe).

The fix is to not listen for platform events if the commissioning window is
closed.

src/app/server/CommissioningWindowManager.cpp

@@ -129,6 +129,8 @@ void CommissioningWindowManager::ResetState()
 
     DeviceLayer::SystemLayer().CancelTimer(HandleCommissioningWindowTimeout, this);
     mCommissioningTimeoutTimerArmed = false;
+
+    DeviceLayer::PlatformMgr().RemoveEventHandler(OnPlatformEventWrapper, reinterpret_cast<intptr_t>(this));
 }
 
 void CommissioningWindowManager::Cleanup()