### 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)
_THREAD_SAFE_METHOD_
	ShapedTextDataAdvanced *sd = shaped_owner.get_or_null(p_shaped);
	ERR_FAIL_COND_V(!sd, false);
	MutexLock lock(sd->mutex);
	if (sd->valid) {
		return true;
	}
	invalidate(sd, false);
	if (sd->parent != RID()) {
		_shaped_text_shape(sd->parent);
		ShapedTextDataAdvanced *parent_sd = shaped_owner.get_or_null(sd->parent);
		ERR_FAIL_COND_V(!parent_sd->valid, false);
		ERR_FAIL_COND_V(!_shape_substr(sd, parent_sd, sd->start, sd->end - sd->start), false);
		return true;
	}
	if (sd->text.length(
		sd->valid = true;
		return true;
	}
	sd->utf16 = sd->text.utf16();
	const UChar *data = sd->utf16.get_data();
	
	if (sd->script_iter == nullptr) {
		sd->script_iter = memnew(ScriptIterator(sd->text, 0, sd->text.length()));
	}
	sd->base_para_direction = UBIDI_DEFAULT_LTR;
	switch (sd->direction) {
		case DIRECTION_LTR: {
			sd->para_direction = DIRECTION_LTR;
			sd->base_para_direction = UBIDI_LTR;