### Godot version

4.x

### System information

Windows 10

### Issue description

The `Search Result` panel is not correctly updated when changing the theme.

https://user-images.githubusercontent.com/66004280/208964493-d0423b78-3418-44c9-95ed-822fd34c4720.mp4



### Steps to reproduce

1. Search something
2. Change the theme

### Minimal reproduction project

--
#include "find_in_files.h"
#include "core/config/project_settings.h"
#include "core/io/dir_access.h"
#include "core/os/os.h"
#include "editor/editor_node.h"
#include "editor/editor_scale.h"
#include "scene/gui/box_container.h"
#include "scene/gui/button.h"
#include "scene/gui/check_box.h"
#include "scene/gui/file_dialog.h"
#include "scene/gui/grid_container.h"
#include "scene/gui/label.h"
#include "scene/gui/line_edit.h"
#include "scene/gui/progress_bar.h"
#include "scene/gui/tree.h"
const char *FindInFiles::SIGNAL_RESULT_FOUND = "result_found";
const char *FindInFiles::SIGNAL_FINISHED = "finished";
template <typename T>
inline void pop_back(T &container) {