Show correct name of signal when editing an existing one

Use popup_dialog() instead of popup_centered() to show edit dialog/

With popup_centered it is not possible to change the displayed
signal name. When this is not set the previous shown name is show
for the current dialog.

This is no problem when creating a new conenction as popop_dialog
is used there and this would update the title.

Fixes #42074

(cherry picked from commit eeb6c2e22c56f988a72cdc6455e55d6039d652fc)

editor/connections_dialog.cpp

@@ -742,8 +742,9 @@ void ConnectionsDock::_open_connection_dialog(Connection cToEdit) {
 	Node *dst = static_cast<Node *>(cToEdit.target);
 
 	if (src && dst) {
+		const String &signalname = cToEdit.signal;
 		connect_dialog->set_title(TTR("Edit Connection:") + cToEdit.signal);
-		connect_dialog->popup_centered();
+		connect_dialog->popup_dialog(signalname);
 		connect_dialog->init(cToEdit, true);
 	}
 }