### 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_V(!fd, String());
	MutexLock lock(fd->mutex);
	if (fd->cache.is_empty()) {
		ERR_FAIL_COND_V(!_ensure_cache_for_size(fd, fd->msdf ? Vector2i(fd->msdf_source_size, 0) : Vector2i(16, 0)), String());
	}
	FontForSizeAdvanced *at_size = fd->cache.begin()->value;
	String chars;
#ifdef MODULE_FREETYPE_ENABLED
	if (at_size && at_size->face) {
		FT_UInt gindex;
		FT_ULong charcode = FT_Get_First_Char(at_size->face, &gindex);
		while (gindex != 0) {
			if (charcode != 0) {
				chars = chars + String::chr(charcode);
			}
			charcode = FT_Get_Next_Char(at_size->face, charcode, &gindex);
		}
		return chars;
	}
#endif
	if (at_size) {
		const HashMap<int32_t, FontGlyph> &gl = at_size->glyph_map;
		for (const KeyValue<int32_t, FontGlyph> &E : gl) {
			chars = chars + String::chr(E.key);
		}
	}
	return chars;
}
void TextServerAdvanced::_font_render_range(const RID &p_font_rid, const Vector2i &p_size, int64_t p_start, int64_t p_end) {