No longer create two instances of the setting view.

This caused a bunch of issues with the getPluginId, as one of the instances
didn't got added to the registry (and as such, never got an ID)

CURA-5829

plugins/SimulationView/__init__.py

@@ -25,4 +25,4 @@ def createSimulationViewProxy(engine, script_engine):
 def register(app):
     simulation_view = SimulationView.SimulationView()
     qmlRegisterSingletonType(SimulationViewProxy.SimulationViewProxy, "UM", 1, 0, "SimulationView", simulation_view.getProxy)
-    return { "view": SimulationView.SimulationView()}
+    return { "view": simulation_view}