### 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)
fd->oversampling = 1.0;
			fd->size.x = p_font_data->msdf_source_size;
		} else if (p_font_data->oversampling <= 0.0) {
			fd->oversampling = _font_get_global_oversampling();
		} else {
			fd->oversampling = p_font_data->oversampling;
		}
		if (FT_HAS_COLOR(fd->face) && fd->face->num_fixed_sizes > 0) {
			int best_match = 0;
			int diff = ABS(fd->size.x - ((int64_t)fd->face->available_sizes[0].width));
			fd->scale = double(fd->size.x * fd->oversampling) / fd->face->available_sizes[0].width;
			for (int i = 1; i < fd->face->num_fixed_sizes; i++) {
				int ndiff = ABS(fd->size.x - ((int64_t)fd->face->available_sizes[i].width));
				if (ndiff < diff) {
					best_match = i;
					diff = ndiff;
					fd->scale = double(fd->size.x * fd->oversampling) / fd->face->available_sizes[i].width;
				}
			}
			FT_Select_Size(fd->face, best_match);
		} else {
			FT_Set_Pixel_Sizes(fd->face, 0, double(fd->size.x * fd->oversampling));
			if (fd->face->size->metrics.y_ppem != 0) {
				fd->scale = ((double)fd->size.x * fd->oversampling) / (double)fd->face->size->metrics.y_ppem;
			}
		}
		fd->hb_handle = hb_ft_font_create(fd->face, nullptr);
		fd->ascent = (fd->face->size->metrics.ascender / 64.0) / fd->oversampling * fd->scale;
		fd->descent = (-fd->face->size->metrics.descender / 64.0) / fd->oversampling * fd->scale;
		fd->underline_position = (-FT_MulFix(fd->face->underline_position, fd->face->size->metrics.y_scale) / 64.0) / fd->oversampling * fd->scale;