Make sure that we are disconnected before dtor

The child class removes itself from the parent panel, which calls the
DTOR.  This automatically disconnects the events, so if we want to
explicitly do this, we need to do it before freeing the memory

Fixes https://gitlab.com/kicad/code/kicad/-/issues/21307

pcbnew/dialogs/panel_assign_component_classes.cpp

@@ -604,11 +604,10 @@ PANEL_COMPONENT_CLASS_CONDITION_REFERENCE::PANEL_COMPONENT_CLASS_CONDITION_REFER
 
 void PANEL_COMPONENT_CLASS_CONDITION_REFERENCE::OnDeleteConditionClick( wxCommandEvent& event )
 {
-    m_panelParent->RemoveCondition( this );
-
     Disconnect( wxEVT_MENU,
                 wxCommandEventHandler( PANEL_COMPONENT_CLASS_CONDITION_REFERENCE::onMenu ), nullptr,
                 this );
+    m_panelParent->RemoveCondition( this );
 }