### 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 (p_direction == HB_DIRECTION_RTL || p_direction == HB_DIRECTION_BTT) {
		gl.flags |= TextServer::GRAPHEME_IS_RTL;
	}
	gl.font_rid = p_font;
	gl.font_size = p_font_size;
	if (glyph_count > 0) {
		if (p_sd->orientation == ORIENTATION_HORIZONTAL) {
			if (subpos) {
				gl.advance = (double)glyph_pos[0].x_advance / (64.0 / scale) + _get_extra_advance(p_font, p_font_size);
			} else {
				gl.advance = Math::round((double)glyph_pos[0].x_advance / (64.0 / scale) + _get_extra_advance(p_font, p_font_size));
			}
		} else {
			gl.advance = -Math::round((double)glyph_pos[0].y_advance / (64.0 / scale));
		}
		gl.count = 1;
		gl.index = glyph_info[0].codepoint;
		if (subpos) {
			gl.x_off = (double)glyph_pos[0].x_offset / (64.0 / scale);
		} else {
			gl.x_off = Math::round((double)glyph_pos[0].x_offset / (64.0 / scale));
		}
		gl.y_off = -Math::round((double)glyph_pos[0].y_offset / (64.0 / scale));
		if ((glyph_info[0].codepoint != 0) || !u_isgraph(p_char)) {
			gl.flags |= GRAPHEME_IS_VALID;
		}
	}
	return gl;
}
_FORCE_INLINE_ void TextServerAdvanced::_add_featuers(const Dictionary &p_source, Vector<hb_feature_t> &r_ftrs) {