Revert "Prevent some unneeded calling of signals"

This reverts commit 85f10e7c4f9bc48afd2fe43903e565b128e03189.
The second time you start Cura, it won't slice due to the number of extruders being wrong.

cura/Settings/ExtruderManager.py

@@ -344,9 +344,7 @@ class ExtruderManager(QObject):
             self._fixSingleExtrusionMachineExtruderDefinition(global_stack)
             if extruders_changed:
                 self.extrudersChanged.emit(global_stack_id)
-
-                # Set it directly instead of using setActiveExtruder, since we want to force the signal to emitted.
-                self._active_extruder_index =  0
+                self.setActiveExtruderIndex(0)
                 self.activeExtruderChanged.emit()
 
     # After 3.4, all single-extrusion machines have their own extruder definition files instead of reusing

cura/Settings/MachineManager.py

@@ -385,6 +385,7 @@ class MachineManager(QObject):
         self._application.setGlobalContainerStack(global_stack)
         ExtruderManager.getInstance()._globalContainerStackChanged()
         self._initMachineState(global_stack)
+        self._onGlobalContainerChanged()
 
         self.__emitChangedSignals()
 

cura/Settings/SettingInheritanceManager.py

@@ -249,6 +249,7 @@ class SettingInheritanceManager(QObject):
         if self._global_container_stack:
             self._global_container_stack.containersChanged.connect(self._onContainersChanged)
             self._global_container_stack.propertyChanged.connect(self._onPropertyChanged)
+        self._onActiveExtruderChanged()
 
     def _onContainersChanged(self, container):
         self._update_timer.start()