### 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)
hb_font_t *hb_font = _font_get_hb_handle(p_font, p_font_size);
	double scale = _font_get_scale(p_font, p_font_size);
	bool subpos = (scale != 1.0) || (_font_get_subpixel_positioning(p_font) == SUBPIXEL_POSITIONING_ONE_HALF) || (_font_get_subpixel_positioning(p_font) == SUBPIXEL_POSITIONING_ONE_QUARTER) || (_font_get_subpixel_positioning(p_font) == SUBPIXEL_POSITIONING_AUTO && p_font_size <= SUBPIXEL_POSITIONING_ONE_HALF_MAX_SIZE);
	ERR_FAIL_COND_V(hb_font == nullptr, Glyph());
	hb_buffer_clear_contents(p_sd->hb_buffer);
	hb_buffer_set_direction(p_sd->hb_buffer, p_direction);
	hb_buffer_set_flags(p_sd->hb_buffer, (hb_buffer_flags_t)(HB_BUFFER_FLAG_DEFAULT));
	hb_buffer_set_script(p_sd->hb_buffer, p_script);
	hb_buffer_add_utf32(p_sd->hb_buffer, (const uint32_t *)&p_char, 1, 0, 1);
	hb_shape(hb_font, p_sd->hb_buffer, nullptr, 0);
	unsigned int glyph_count = 0;
	hb_glyph_info_t *glyph_info = hb_buffer_get_glyph_infos(p_sd->hb_buffer, &glyph_count);
	hb_glyph_position_t *glyph_pos = hb_buffer_get_glyph_positions(p_sd->hb_buffer, &glyph_count);
	
	Glyph gl;