Fix reselecting scene tree node after inspecting a resource

This broke when the `node_selected` connection was removed in #91435.
Here it's returned, but the emit is removed from `_node_removed`. That
preserves the earlier fix while allowing nodes to be reselected.

editor/gui/scene_tree_editor.cpp

@@ -589,7 +589,6 @@ void SceneTreeEditor::_node_removed(Node *p_node) {
 
 	if (p_node == selected) {
 		selected = nullptr;
-		emit_signal(SNAME("node_selected"));
 	}
 }