### 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)

if (ClassDB::has_signal(p_native_type_string, p_member_name)) {
		return true;
	}
	if (ClassDB::has_property(p_native_type_string, p_member_name)) {
		return true;
	}
	if (ClassDB::has_integer_constant(p_native_type_string, p_member_name)) {
		return true;
	}
	if (p_member_name == CoreStringNames::get_singleton()->_script) {
		return true;
	}
	return false;
}
Error GDScriptAnalyzer::check_native_member_name_conflict(const StringName &p_member_name, const GDScriptParser::Node *p_member_node, const StringName &p_native_type_string) {
	if (has_member_name_conflict_in_native_type(p_member_name, p_native_type_string)) {
		push_error(vformat(R"(Member "%s" redefined (original in native class '%s'))", p_member_name, p_native_type_string), p_member_node);
		return ERR_PARSE_ERROR;
	}
	if (class_exists(p_member_name)) {
		push_error(vformat(R"(The member "%s" shadows a native class.)", p_member_name), p_member_node);
		return ERR_PARSE_ERROR;
	}
	if (GDScriptParser::get_builtin_type(p_member_name) != Variant::VARIANT_MAX) {
		push_error(vformat(R"(The member "%s" cannot have the same name as a builtin type.)", p_member_name), p_member_node);
		return ERR_PARSE_ERROR;
	}
	return OK;
}
Error GDScriptAnalyzer::check_class_member_name_conflict(const GDScriptParser::ClassNode *p_class_node, const StringName &p_member_name, const GDScriptParser::Node *p_member_node) {