### 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 bad_type;
	bad_type.kind = GDScriptParser::DataType::VARIANT;
	bad_type.type_source = GDScriptParser::DataType::INFERRED;
	if (p_type == nullptr) {
		return bad_type;
	}
	if (p_type->get_datatype().is_resolving()) {
		push_error(R"(Could not resolve datatype: Cyclic reference.)", p_type);
		return bad_type;
	}
	if (!p_type->get_datatype().has_no_type()) {
		return p_type->get_datatype();
	}
	GDScriptParser::DataType resolving_datatype;
	resolving_datatype.kind = GDScriptParser::DataType::RESOLVING;
	p_type->set_datatype(resolving_datatype);
	GDScriptParser::DataType result;
	result.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
	if (p_type->type_chain.is_empty()) {
		
		result.kind = GDScriptParser::DataType::BUILTIN;
		result.builtin_type = Variant::NIL;