Rename setVariantGroup() -> setVariant()

There is no such thing as VariantGroup.

cura/Settings/MachineManager.py

@@ -1227,7 +1227,7 @@ class MachineManager(QObject):
             self._updateQualityWithMaterial()
 
     @pyqtSlot(str, "QVariant")
-    def setVariantGroup(self, position, container_node):
+    def setVariant(self, position, container_node):
         position = str(position)
         self.blurSettings.emit()
         with postponeSignals(*self._getContainerChangedSignals(), compress = CompressTechnique.CompressPerParameterValue):

resources/qml/Menus/NozzleMenu.qml

@@ -32,7 +32,7 @@ Menu
             }
             exclusiveGroup: group
             onTriggered: {
-                Cura.MachineManager.setVariantGroup(menu.extruderIndex, model.container_node);
+                Cura.MachineManager.setVariant(menu.extruderIndex, model.container_node);
             }
         }