### 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)
ert("ks_Arab"));
		ert("ks_Arab_IN"));
		ert("lrc")); // Northern Luri
		ert("lrc_IQ"));
		ert("lrc_IR"));
		ert("mzn")); // Mazanderani
		ert("mzn_IR"));
		ert("pa_PK")); // Panjabi
		ert("pa_Arab"));
		ert("pa_Arab_PK"));
		ert("ps")); // Pushto
		ert("ps_AF"));
		ert("ps_PK"));
		ert("ur_IN")); // Urdu
		ert("uz_AF")); // Uzbek
		ert("uz_Arab"));
		ert("uz_Arab_AF"));
		pr.digits = U"۰۱۲۳۴۵۶۷۸۹٫";
		prsign = U"٪";
		pr.exp = U"اس";
		num_systems.push_back(pr);
	}
	// Bengali numerals.
	{
		NumSystemData bn;
		bnert("as")); // Assamese
		bnert("as_IN"));
		bnert("bn")); // Bengali
		bnert("bn_BD"));
		bnert("bn_IN"));