### 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)
}
		if ( == SEQ_NOT_STARTED) {
			if (cat == U_UPPERER || cat == U_LOWERER || cat == U_TITLEER || cat == U_MODIFIER_LETTER || cat == U_OTHER_LETTER) {
				 = SEQ_STARTED;
				B_scr = scr;
			}
		}
		if (u_hasBinaryProperty(str[i], UCHAR_PATTERN_SYNTAX) || u_hasBinaryProperty(str[i], UCHAR_PATTERN_WHITE_SPACE) || u_hasBinaryProperty(str[i], UCHAR_NONCHARACTER_CODE_POINT)) {
			return false; // Not a XID_Start or XID_Continue character.
		}
		if (i 
			if (!(cat == U_LOWERER || cat == U_UPPERER || cat == U_TITLEER || cat == U_OTHER_LETTER || cMBER || str[0] == 0x2118 || str[0] == 0x212E || str[0] == 0x309B || str[0] == 0x309C || str[0] == 0x005F)) {
				return false; // Not a XID_Start character.
			}
		} else {
			if (!(cat == U_LOWERER || cat == U_UPPERER || cat == U_TITLEER || cat == U_OTHER_LETTER || cMBER || cat == U_NON_SPACING_MARK || cat == U_COMBINING_SPACING_MARK || cat == U_DECIMAL_DIGIT_NUMBER || cat == U_CONNECTOR_PUNCTUATION || str[i] == 0x2118 || str[i] == 0x212E || str[i] == 0x309B || str[i] == 0x309C || str[i] == 0x1369 || str[i] == 0x1371 || str[i] == 0x00B7 || str[i] == 0x0387 || str[i] == 0x19DA || str[i] == 0x0E33 || str[i] == 0x0EB3 || str[i] == 0xFF9E || str[i] == 0xFF9F)) {
				return false; // Not a XID_Continue character.
			}
		}
	}
	return true;
}
TextServerAdvanced::TextServerAdvanced() {
	_insert_num_systems_lang();
	_insert_feature_sets();
	_bmp_create_font_funcs();
}
up() {
	_THREAD_SAFE_METHOD_
	for (const KeyValue<SystemFontKey, SystemFontCache> &E : system_fonts) {