### 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(!fd);
	MutexLock lock(fd->mutex);
	MutexLock ftlock(ft_mutex);
	if (fd->cache.has(p_size)) {
		memdelete(fd->cache[p_size]);
		fd->cache.erase(p_size);
	}
}
void TextServerAdvanced::_font_set_ascent(const RID &p_font_rid, int64_t p_size, double p_ascent) {
	FontAdvanced *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND(!fd);
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size(fd, p_size);
	ERR_FAIL_COND(!_ensure_cache_for_size(fd, size));
	fd->cache[size]->ascent = p_ascent;
}
double TextServerAdvanced::_font_get_ascent(const RID &p_font_rid, int64_t p_size) const {
	FontAdvanced *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND_V(!fd, 0.0);
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size(fd, p_size);
	ERR_FAIL_COND_V(!_ensure_cache_for_size(fd, size), 0.0);
	if (fd->msdf) {
		return fd->cache[size]->ascent * (double)p_size / (double)fd->msdf_source_size;
	} else {
		return fd->cache[size]->ascent;
	}
}
void TextServerAdvanced::_font_set_descent(const RID &p_font_rid, int64_t p_size, double p_descent) {