Shut down InteractionModelEngine during DeviceController shutdown. (#…

…7629)

Otherwise if we have an IM action in flight at shutdown time we will
effectively leak the object managing it, and after a few
shutdown/restart cycles for the stack not be able to send any more IM
actions.

src/controller/CHIPDeviceController.cpp

@@ -312,6 +312,10 @@ CHIP_ERROR DeviceController::Shutdown()
 
     mState = State::NotInitialized;
 
+    // Shut down the interaction model before we try shuttting down the exchange
+    // manager.
+    app::InteractionModelEngine::GetInstance()->Shutdown();
+
     // TODO(#6668): Some exchange has leak, shutting down ExchangeManager will cause a assert fail.
     // if (mExchangeMgr != nullptr)
     // {