### 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)

GDScriptParser::DataType type;
	type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
	type.kind = GDScriptParser::DataType::BUILTIN;
	type.builtin_type = Variant::CALLABLE;
	type.is_constant = true;
	type.method_info = p_info;
	return type;
}
static GDScriptParser::DataType make_signal_type(const MethodInfo &p_info) {
	GDScriptParser::DataType type;
	type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
	type.kind = GDScriptParser::DataType::BUILTIN;
	type.builtin_type = Variant::SIGNAL;
	type.is_constant = true;
	type.method_info = p_info;
	return type;
}
static GDScriptParser::DataType make_native_meta_type(const StringName &p_class_name) {
	GDScriptParser::DataType type;
	type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
	type.kind = GDScriptParser::DataType::NATIVE;
	type.builtin_type = Variant::OBJECT;
	type.native_type = p_class_name;
	type.is_constant = true;
	type.is_meta_type = true;
	return type;
}
static GDScriptParser::DataType make_script_meta_type(const Ref<Script> &p_script) {