### 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);
	Vector2i size = _get_size_outline(fd, p_size);
	ERR_FAIL_COND(!_ensure_cache_for_size(fd, size));
	HashMap<int32_t, FontGlyph> &gl = fd->cache[size]->glyph_map;
	gl[p_glyph].uv_rect = p_uv_rect;
	gl[p_glyph].found = true;
}
int64_t TextServerAdvanced::_font_get_glyph_texture_idx(const RID &p_font_rid, const Vector2i &p_size, int64_t p_glyph) const {
	FontAdvanced *fd = font_owner.get_or_null(p_font_rid);
	ERR_FAIL_COND_V(!fd, -1);
	MutexLock lock(fd->mutex);
	Vector2i size = _get_size_outline(fd, p_size);
	ERR_FAIL_COND_V(!_ensure_cache_for_size(fd, size), -1);
	int mod = 0;
	if (fd->antialiasing == FONT_ANTIALIASING_LCD) {
		TextServer::FontLCDSubpixelLayout layout = (TextServer::FontLCDSubpixelLayout)(int)GLOBAL_GET("gui/theme/lcd_subpixel_layout");
		if (layout != FONT_LCD_SUBPIXEL_LAYOUT_NONE) {
			mod = (layout << 24);
		}
	}
	if (!_ensure_glyph(fd, size, p_glyph | mod)) {
		return -1; 
	}
	const HashMap<int32_t, FontGlyph> &gl = fd->cache[size]->glyph_map;
	return gl[p_glyph | mod].texture_idx;
}
void TextServerAdvanced::_font_set_glyph_texture_idx(const RID &p_font_rid, const Vector2i &p_size, int64_t p_glyph, int64_t p_texture_idx) {