Remove definitionChanges before removing a printer

When removing a printer, the files in %appdata%/cura/<version>/
/definition_changes/ remained intact. This commit fixes that by
making sure that the definitionChanges are removed before removing
the machine.

cura/Settings/ExtruderManager.py

@@ -302,6 +302,7 @@ class ExtruderManager(QObject):
 
         for extruder in self.getMachineExtruders(machine_id):
             ContainerRegistry.getInstance().removeContainer(extruder.userChanges.getId())
+            ContainerRegistry.getInstance().removeContainer(extruder.definitionChanges.getId())
             ContainerRegistry.getInstance().removeContainer(extruder.getId())
         if machine_id in self._extruder_trains:
             del self._extruder_trains[machine_id]

cura/Settings/MachineManager.py

@@ -720,6 +720,8 @@ class MachineManager(QObject):
         containers = CuraContainerRegistry.getInstance().findInstanceContainersMetadata(type = "user", machine = machine_id)
         for container in containers:
             CuraContainerRegistry.getInstance().removeContainer(container["id"])
+        machine_stack = CuraContainerRegistry.getInstance().findContainerStacks(type = "machine", name = machine_id)[0]
+        CuraContainerRegistry.getInstance().removeContainer(machine_stack.definitionChanges.getId())
         CuraContainerRegistry.getInstance().removeContainer(machine_id)
 
         # If the printer that is being removed is a network printer, the hidden printers have to be also removed