### 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_NULL(p_identifier);
	p_identifier->set_datatype(p_identifier_datatype);
	Error err = OK;
	Ref<GDScript> scr = GDScriptCache::get_shallow_script(p_identifier_datatype.script_path, err);
	if (err) {
		push_error(vformat(R"(Error while getting cache for script "%s".)", p_identifier_datatype.script_path), p_identifier);
		return;
	}
	p_identifier->reduced_value = scr->find_class(p_identifier_datatype.class_type->fqcn);
	p_identifier->is_constant = true;
}
void GDScriptAnalyzer::reduce_identifier_from_base(GDScriptParser::IdentifierNode *p_identifier, GDScriptParser::DataType *p_base) {
	if (!p_identifier->get_datatype().has_no_type()) {
		return;
	}
	GDScriptParser::DataType base;
	if (p_base == nullptr) {
		base = type_from_metatype(parser->current_class->get_datatype());
	} else {
		base = *p_base;
	}
	StringName name = p_identifier->name;
	if (base.kind == GDScriptParser::DataType::ENUM) {
		if (base.is_meta_type) {
			if (base.enum_values.has(name)) {