### 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)
p_new_sd->descent = MAX(p_new_sd->descent, Math::round(_font_get_glyph_advance(gl.font_rid, gl.font_size, gl.index).x * 0.5));
								}
							} else if (p_new_sd->preserve_invalid || (p_new_sd->preserve_control && is_control(gl.index))) {
								
								if (p_new_sd->orientation == ORIENTATION_HORIZONTAL) {
									p_new_sd->ascent = MAX(p_new_sd->ascent, get_hex_code_box_size(gl.font_size, gl.index).y);
								} else {
									p_new_sd->ascent = MAX(p_new_sd->ascent, Math::round(get_hex_code_box_size(gl.font_size, gl.index).x * 0.5));
									p_new_sd->descent = MAX(p_new_sd->descent, Math::round(get_hex_code_box_size(gl.font_size, gl.index).x * 0.5));
								}
							}
							p_new_sd->width += gl.advance * gl.repeat;
						}
						p_new_sd->glyphs.push_back(gl);
					}
				}
			}
		}
		_realign(p_new_sd);
	}
	p_new_sd->valid = true;
	return true;
}
RID TextServerAdvanced::_shaped_text_get_parent(const RID &p_shaped) const {
	ShapedTextDataAdvanced *sd = shaped_owner.get_or_null(p_shaped);
	ERR_FAIL_COND_V(!sd, RID());
	MutexLock lock(sd->mutex);
	return sd->parent;
}
double TextServerAdvanced::_shaped_text_fit_to_width(const RID &p_shaped, double p_width, BitField<TextServer::JustificationFlag> p_jst_flags) {