### Godot version

v4.2.dev4.official [549fcce5f]

### System information

Ubuntu 20.04 LTS

### Issue description

See title.

### Steps to reproduce

1. Create a new project
2. Create a csv file that includes the following
```
key,ar
key,placeholder
```
3. Add the generated `.translation` file to Project -> Project Settings... -> Localization
4. In Project -> Project Settings... -> Internationalization -> Locale, set `Test` to `ar`
5. Add a `LineEdit` node and type `-=[]{}`
6. Run the project, and notice that the text is on the right side, but the symbols are incorrectly in LTR (`-=[]{}`).  Correct output is `{}[]=-`
7. Back in the editor, add a single Arabic letter (any will do), and notice that `LineEdit` immediately (and correctly) flips the symbols, and the newly-added Arabic letter, to RTL.

**Notes**
- Identical behavior is seen with `TextEdit`.
- The purpose of steps 2-4 are to simulate an Arabic environment when the project is run, despite `OS.get_locale() == "en"` (or your system's current language).

### Minimal reproduction project

[rtlsymbols.zip](https://github.com/godotengine/godot/files/12525509/rtlsymbols.zip)
const bmp_font_t *bm_font = static_cast<const bmp_font_t *>(p_font_data);
	if (!bm_font->face) {
		return 0;
	}
	if (!bm_font->face->glyph_map.has(p_glyph)) {
		return 0;
	}
	return bm_font->face->glyph_map[p_glyph].advance.x * 64;
}
hb_position_t TextServerAdvanced::_bmp_get_glyph_v_advance(hb_font_t *p_font, void *p_font_data, hb_codepoint_t p_glyph, void *p_user_data) {
	const bmp_font_t *bm_font = static_cast<const bmp_font_t *>(p_font_data);
	if (!bm_font->face) {
		return 0;
	}
	if (!bm_font->face->glyph_map.has(p_glyph)) {
		return 0;
	}
	return -bm_font->face->glyph_map[p_glyph].advance.y * 64;
}
hb_position_t TextServerAdvanced::_bmp_get_glyph_h_kerning(hb_font_t *p_font, void *p_font_data, hb_codepoint_t p_left_glyph, hb_codepoint_t p_right_glyph, void *p_user_data) {
	const bmp_font_t *bm_font = static_cast<const bmp_font_t *>(p_font_data);
	if (!bm_font->face) {
		return 0;
	}
	if (!bm_font->face->kerning_map.has(Vector2i(p_left_glyph, p_right_glyph))) {
		return 0;
	}
	return bm_font->face->kerning_map[Vector2i(p_left_glyph, p_right_glyph)].x * 64;
}
hb_bool_t TextServerAdvanced::_bmp_get_glyph_v_origin(hb_font_t *p_font, void *p_font_data, hb_codepoint_t p_glyph, hb_position_t *r_x, hb_position_t *r_y, void *p_user_data) {