### 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 (source == nullptr) {
		return;
	}
	GDScriptParser::DataType datatype;
	datatype.kind = GDScriptParser::DataType::VARIANT;
	source->set_datatype(datatype);
}
void GDScriptAnalyzer::mark_lambda_use_self() {
	for (GDScriptParser::LambdaNode *lambda : lambda_stack) {
		lambda->use_self = true;
	}
}
bool GDScriptAnalyzer::class_exists(const StringName &p_class) const {
	return ClassDB::class_exists(p_class) && ClassDB::is_class_exposed(p_class);
}
Ref<GDScriptParserRef> GDScriptAnalyzer::get_parser_for(const String &p_path) {
	Ref<GDScriptParserRef> ref;
	if (depended_parsers.has(p_path)) {
		ref = depended_parsers[p_path];
	} else {
		Error err = OK;
		ref = GDScriptCache::get_parser(p_path, GDScriptParserRef::EMPTY, err, parser->script_path);
		if (ref.is_valid()) {
			depended_parsers[p_path] = ref;
		}
	}
	return ref;
}
Error GDScriptAnalyzer::resolve_inheritance() {