Prevent resizing minimap bigger than GraphEdit (Fix #47189)

Minimap size couldn't be resized back after been resized bigger than GraphEdit cause the grabber was out of GraphEdit.
This commit prevents resizing minimap bigger than GraphEdit and fix this issue.

(cherry picked from commit 045f55ec00d7358cc496474fd68ab47bda9a83a7)

scene/gui/graph_edit.cpp

@@ -181,7 +181,12 @@ void GraphEditMinimap::_gui_input(const Ref<InputEvent> &p_ev) {
 		accept_event();
 	} else if (mm.is_valid() && is_pressing) {
 		if (is_resizing) {
-			ge->set_minimap_size(ge->get_minimap_size() - mm->get_relative());
+			// Prevent setting minimap wider than GraphEdit
+			Vector2 new_minimap_size;
+			new_minimap_size.x = MIN(get_size().x - mm->get_relative().x, ge->get_size().x - 2.0 * minimap_padding.x);
+			new_minimap_size.y = MIN(get_size().y - mm->get_relative().y, ge->get_size().y - 2.0 * minimap_padding.y);
+			ge->set_minimap_size(new_minimap_size);
+
 			update();
 		} else {
 			Vector2 click_position = _convert_to_graph_position(mm->get_position() - minimap_padding) - graph_padding;