### 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)
for (unsigned int j = last_cluster_index; j < i; j++) {
						w[j].end = glyph_info[i].cluster;
					}
				}
				if (p_direction == HB_DIRECTION_RTL || p_direction == HB_DIRECTION_BTT) {
					w[last_cluster_index].flags |= GRAPHEME_IS_RTL;
				}
				if (last_cluster_valid) {
					w[last_cluster_index].flags |= GRAPHEME_IS_VALID;
				}
				w[last_cluster_index].count = i - last_cluster_index;
				last_cluster_index = i;
				last_cluster_valid = true;
			}
			last_cluster_id = glyph_info[i].cluster;
			Glyph &gl = w[i];
			gl = Glyph();
			gl.start = glyph_info[i].cluster;
			gl.end = end;
			gl.count = 0;
			gl.font_rid = f;
			gl.font_size = fs;
			if (glyph_info[i].mask & HB_GLYPH_FLAG_UNSAFE_TO_BREAK) {
				gl.flags |= GRAPHEME_IS_CONNECTED;
			}
#if HB_VERSION_ATLEAST(5, 1, 0)
			if (glyph_info[i].mask & HB_GLYPH_FLAG_SAFE_TO_INSERT_TATWEEL) {
				gl.flags |= GRAPHEME_IS_SAFE_TO_INSERT_TATWEEL;
			}
#endif