### 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)
}
	if (!f.is_valid()) {
		
		for (int i = p_start; i < p_end; i++) {
			if (p_sd->preserve_invalid || (p_sd->preserve_control && is_control(p_sd->text[i]))) {
				Glyph gl;
				gl.start = i + p_sd->start;
				gl.end = i + 1 + p_sd->start;
				gl.count = 1;
				gl.index = p_sd->text[i];
				gl.font_size = fs;
				gl.font_rid = RID();
				if (p_direction == HB_DIRECTION_RTL || p_direction == HB_DIRECTION_BTT) {
					gl.flags |= TextServer::GRAPHEME_IS_RTL;
				}
				if (p_sd->orientation == ORIENTATION_HORIZONTAL) {
					gl.advance = get_hex_code_box_size(fs, gl.index).x;
					p_sd->ascent = MAX(p_sd->ascent, get_hex_code_box_size(fs, gl.index).y);
				} else {
					gl.advance = get_hex_code_box_size(fs, gl.index).y;
					gl.y_off = get_hex_code_box_size(fs, gl.index).y;
					gl.x_off = -Math::round(get_hex_code_box_size(fs, gl.index).x * 0.5);
					p_sd->ascent = MAX(p_sd->ascent, Math::round(get_hex_code_box_size(fs, gl.index).x * 0.5));
					p_sd->descent = MAX(p_sd->descent, Math::round(get_hex_code_box_size(fs, gl.index).x * 0.5));
				}
				p_sd->width += gl.advance;
				p_sd->glyphs.push_back(gl);
			}
		}
		return;