### 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 (!_shape_substr(new_sd, sd, p_start, p_length)) {
		memdelete(new_sd);
		return RID();
	}
	return shaped_owner.make_rid(new_sd);
}
bool TextServerAdvanced::_shape_substr(ShapedTextDataAdvanced *p_new_sd, const ShapedTextDataAdvanced *p_sd, int64_t p_start, int64_t p_length) const {
	if (p_new_sd->valid) {
		return true;
	}
	p_new_sd->hb_buffer = hb_buffer_create();
	p_new_sd->line_breaks_valid = p_sd->line_breaks_valid;
	p_new_sd->justification_ops_valid = p_sd->justification_ops_valid;
	p_new_sd->sort_valid = false;
	p_new_sd->upos = p_sd->upos;
	p_new_sd->uthk = p_sd->uthk;
	if (p_length > 0) {
		p_new_sd->text = p_sd->text.substr(p_start - p_sd->start, p_length);
		p_new_sd->utf16 = p_new_sd->text.utf16();
		p_new_sd->script_iter = memnew(ScriptIterator(p_new_sd->text, 0, p_new_sd->text.length()));
		int sd_size = p_sd->glyphs.size();
		const Glyph *sd_glyphs = p_sd->glyphs.ptr();
		for (int ov = 0; ov < p_sd->bidi_override.size(); ov++) {
			UErrorCode err = U_ZERO_ERROR;
			if (p_sd->bidi_override[ov].x >= p_start + p_length || p_sd->bidi_override[ov].y <= p_start) {
				continue;
			}
			int ov_start = _convert_pos_inv(p_sd, p_sd->bidi_override[ov].x);
			int start = MAX(0, _convert_pos_inv(p_sd, p_start) - ov_start);