### 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)
FontAdvanced *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND_V(!fd, 0);
	ERR_FAIL_COND_V_MSG((p_char >= 0xd800 && p_char <= 0xdfff) || (p_char > 0x10ffff), 0, "Unicode parsing error: Invalid unicode codepoint " + String::num_int64(p_char, 16) + ".");
	ERR_FAIL_COND_V_MSG((p_variation_selector >= 0xd800 && p_variation_selector <= 0xdfff) || (p_variation_selector > 0x10ffff), 0, "Unicode parsing error: Invalid unicode codepoint " + String::num_int64(p_variation_selector, 16) + ".");
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size(fd, p_size);
	ERR_FAIL_COND_V(!_ensure_cache_for_size(fd, size), 0);
#ifdef MODULE_FREETYPE_ENABLED
	if (fd->cache[size]->face) {
		if (p_variation_selector) {
			return FT_Face_GetCharVariantIndex(fd->cache[size]->face, p_char, p_variation_selector);
		} else {
			return FT_Get_Char_Index(fd->cache[size]->face, p_char);
		}
	} else {
		return (int64_t)p_char;
	}
#else
	return (int64_t)p_char;
#endif
}
int64_t TextServerAdvanced::_font_get_char_from_glyph_index(const RID &p_font_rid, int64_t p_size, int64_t p_glyph_index) const {