### 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)
ShapedTextDataAdvanced *sd = shaped_owner.get_or_null(p_shaped);
	ERR_FAIL_COND_V(!sd, false);
	ERR_FAIL_COND_V(p_size <= 0, false);
	MutexLock lock(sd->mutex);
	for (int i = 0; i < p_fonts.size(); i++) {
		ERR_FAIL_COND_V(!font_owner.get_or_null(p_fonts[i]), false);
	}
	if (p_text.is_empty()) {
		return true;
	}
	if (sd->parent != RID()) {
		full_copy(sd);
	}
	ShapedTextDataAdvanced::Span span;
	span.start = sd->text.length();
	span.end = span.start + p_text.length();
	span.fonts = p_fonts; 
	span.font_size = p_size;
	span.language = p_language;
	span.features = p_opentype_features;
	span.meta = p_meta;
	sd->spans.push_back(span);
	sd->text = sd->text + p_text;
	sd->end += p_text.length();
	invalidate(sd, true);
	return true;
}
bool TextServerAdvanced::_shaped_text_add_object(const RID &p_shaped, const Variant &p_key, const Size2 &p_size, InlineAlignment p_inline_align, int64_t p_length, double p_baseline) {