Revert "Make sure toplevel is active in SetFocus()"

This reverts commit d06e97e8d9 as it
resulted in regression in wxSplitterWindow behaviour.

See #18783.

Closes #18845.

src/gtk/window.cpp

@@ -4583,10 +4583,6 @@ void wxWindowGTK::SetFocus()
     if (gs_currentFocus != this)
         gs_pendingFocus = this;
 
-    wxWindow* tlw = wxGetTopLevelParent(static_cast<wxWindow*>(this));
-    if (tlw && tlw->m_widget && !gtk_window_is_active(GTK_WINDOW(tlw->m_widget)))
-        tlw->Raise();
-
     GtkWidget *widget = m_wxwindow ? m_wxwindow : m_focusWidget;
 
     if ( GTK_IS_CONTAINER(widget) &&