### 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)

p_base_type.is_meta_type = false;
		} else {
			push_error("Cannot call function on enum value.", p_source);
			return false;
		}
	}
	if (p_base_type.kind == GDScriptParser::DataType::BUILTIN) {
		
		Callable::CallError err;
		Variant dummy;
		Variant::construct(p_base_type.builtin_type, dummy, nullptr, 0, err);
		if (err.error != Callable::CallError::CALL_OK) {
			ERR_FAIL_V_MSG(false, "Could not construct base Variant type.");
		}
		List<MethodInfo> methods;
		dummy.get_method_list(&methods);
		for (const MethodInfo &E : methods) {
			if (E.name == p_function) {
				function_signature_from_info(E, r_return_type, r_par_types, r_default_arg_count, r_method_flags);
				
				if (!r_method_flags.has_flag(METHOD_FLAG_STATIC) && was_enum && !(E.flags & METHOD_FLAG_CONST)) {
					push_error(vformat(R"*(Cannot call non-const Dictionary function "%s()" on enum "%s".)*", p_function, p_base_type.enum_type), p_source);
				}
				return true;
			}
		}
		return false;
	}
	StringName base_native = p_base_type.native_type;
	if (base_native != StringName()) {