### 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 (feature_sets.has(p_name)) {
		return feature_sets[p_name];
	}
	
	return hb_tag_from_string(p_name.replace("custom_", "").ascii().get_data(), -1);
}
Variant::Type TextServerAdvanced::_get_tag_type(int64_t p_tag) const {
	if (feature_sets_inv.has(p_tag)) {
		return feature_sets_inv[p_tag].vtype;
	}
	return Variant::Type::INT;
}
bool TextServerAdvanced::_get_tag_hidden(int64_t p_tag) const {
	if (feature_sets_inv.has(p_tag)) {
		return feature_sets_inv[p_tag].hidden;
	}
	return false;
}
String TextServerAdvanced::_tag_to_name(int64_t p_tag) const {
	if (feature_sets_inv.has(p_tag)) {
		return feature_sets_inv[p_tag].name;
	}
	
	char name[5];
	memset(name, 0, 5);
	hb_tag_to_string(p_tag, name);
	return String("custom_") + String(name);
}
_FORCE_INLINE_ TextServerAdvanced::FontTexturePosition TextServerAdvanced::find_texture_pos_for_glyph(FontForSizeAdvanced *p_data, int p_color_size, Image::Format p_image_format, int p_width, int p_height, bool p_msdf) const {