Remove wxTextCtrl frame with wxBORDER_NONE for GTK3

This was deleted for GTK3 in 80e2264373 (Fix wxBORDER_NONE handling for
wxTextCtrl under GTK+ 3, 2017-10-31), but there was no harm in keeping it,
and it actually helps with a transitory visual glitch when the widget is
created on a parent that is already showing.
See #24105

src/gtk/textctrl.cpp

@@ -797,11 +797,8 @@ bool wxTextCtrl::Create( wxWindow *parent,
         // new, empty control, see https://github.com/wxWidgets/wxWidgets/issues/11409
         gtk_entry_get_text((GtkEntry*)m_text);
 
-#ifndef __WXGTK3__
         if (style & wxNO_BORDER)
             gtk_entry_set_has_frame((GtkEntry*)m_text, FALSE);
-#endif
-
     }
     g_object_ref(m_widget);