### Godot version

v4.0.rc1.official [8843d9ad3]

### System information

Lubuntu

### Issue description

You can't use + or += to mutate typed arrays.

It seems to be not correctly getting the type information from the second operand.

An erudite poster on the discord puts it differently:
> it's more like operator + doesn't retain Array typing
> the syntax for Array Concatenation via operators, but the idea gets across i think


The error you see is:
```Trying to assign an array of type "Array" to a variable of type "Array[int]".```


### Steps to reproduce

```
	var Alice: Array[int] = [1,2,3]
	var Bob: Array[int] = [4,5,6]
	Alice += Bob
```
This will crash with the above error message.

### Minimal reproduction project

[plus_syntax_broken_demo_project.zip](https://github.com/godotengine/godot/files/10694514/plus_syntax_broken_demo_project.zip)

public:
	_FORCE_INLINE_ static String do_mod(const String &s, const Array &p_values, bool *r_valid) {
		String a = s.sprintf(p_values, r_valid);
		if (r_valid) {
			*r_valid = !*r_valid;
		}
		return a;
	}
	static void evaluate(const Variant &p_left, const Variant &p_right, Variant *r_ret, bool &r_valid) {
		*r_ret = do_mod(*VariantGetInternalPtr<S>::get_ptr(&p_left), *VariantGetInternalPtr<Array>::get_ptr(&p_right), &r_valid);
	}
	static inline void validated_evaluate(const Variant *left, const Variant *right, Variant *r_ret) {
		bool valid = true;
		String result = do_mod(*VariantGetInternalPtr<S>::get_ptr(left), *VariantGetInternalPtr<Array>::get_ptr(right), &valid);
		ERR_FAIL_COND_MSG(!valid, result);
		*VariantGetInternalPtr<String>::get_ptr(r_ret) = result;
	}
	static void ptr_evaluate(const void *left, const void *right, void *r_ret) {
		PtrToArg<String>::encode(do_mod(PtrToArg<S>::convert(left), PtrToArg<Array>::convert(right), nullptr), r_ret);
	}
	static Variant::Type get_return_type() { return Variant::STRING; }
};
template <class S>
class OperatorEvaluatorStringFormat<S, Object> {