### 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)
int bidi_run_count = 1;
		if (bidi_iter) {
			bidi_run_count = ubidi_countRuns(bidi_iter, &err);
			if (U_FAILURE(err)) {
				ERR_PRINT(u_errorName(err));
			}
		}
		for (int i = 0; i < bidi_run_count; i++) {
			int32_t _bidi_run_start = 0;
			int32_t _bidi_run_length = end - start;
			bool is_rtl = false;
			hb_direction_t bidi_run_direction = HB_DIRECTION_INVALID;
			if (bidi_iter) {
				is_rtl = (ubidi_getVisualRun(bidi_iter, i, &_bidi_run_start, &_bidi_run_length) == UBIDI_LTR);
			}
			switch (sd->orientation) {
				case ORIENTATION_HORIZONTAL: {
					if (is_rtl) {
						bidi_run_direction = HB_DIRECTION_LTR;
					} else {
						bidi_run_direction = HB_DIRECTION_RTL;
					}
				} 
				case ORIENTATION_VERTICAL: {
					if (is_rtl) {
						bidi_run_direction = HB_DIRECTION_TTB;
					} else {
						bidi_run_direction = HB_DIRECTION_BTT;
					}
				}