### 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)

ERR_FAIL_COND_V(!Variant::has_utility_function(p_function), MethodInfo());
	MethodInfo info(p_function);
	if (Variant::has_utility_function_return_value(p_function)) {
		info.return_val.type = Variant::get_utility_function_return_type(p_function);
		if (info.return_val.type == Variant::NIL) {
			info.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
		}
	}
	if (Variant::is_utility_function_vararg(p_function)) {
		info.flags |= METHOD_FLAG_VARARG;
	} else {
		for (int i = 0; i < Variant::get_utility_function_argument_count(p_function); i++) {
			PropertyInfo pi;
#ifdef DEBUG_METHODS_ENABLED
			pi.name = Variant::get_utility_function_argument_name(p_function, i);
#else
			pi.name = "arg" + itos(i + 1);
#endif
			pi.type = Variant::get_utility_function_argument_type(p_function, i);
			info.arguments.push_back(pi);
		}
	}
	return info;
}
static GDScriptParser::DataType make_callable_type(const MethodInfo &p_info) {