### 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)
dzsign = U"%";
		dz.exp = U"e";
		num_systems.push_back(dz);
	}
	// Santali numerals.
	{
		NumSystemData sat;
		satert("sat")); // Santali
		satert("sat_IN"));
		satert("sat_Olck"));
		satert("sat_Olck_IN"));
		sat.digits = U"᱐᱑᱒᱓᱔᱕᱖᱗᱘᱙.";
		satsign = U"%";
		sat.exp = U"e";
		num_systems.push_back(sat);
	}
	// Burmese numerals.
	{
		NumSystemData my;
		myert("my")); // Burmese
		myert(;
		my.digits = U"၀၁၂၃၄၅၆၇၈၉.";
		mysign = U"%";
		"e";
		num_systems.push_back(my);
	}
	// Chakma numerals.
	{
		NumSystemData ccp;
		ccpert("ccp")); // Chakma