### 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_COND_V_MSG(!p_target.is_set(), true, "Parser bug (please report): Trying to check compatibility of unset target type");
	ERR_FAIL_COND_V_MSG(!p_source.is_set(), true, "Parser bug (please report): Trying to check compatibility of unset value type");
	if (p_target.kind == GDScriptParser::DataType::VARIANT) {
		
		return true;
	}
	if (p_source.kind == GDScriptParser::DataType::VARIANT) {
		
		return true;
	}
	if (p_target.kind == GDScriptParser::DataType::BUILTIN) {
		bool valid = p_source.kind == GDScriptParser::DataType::BUILTIN && p_target.builtin_type == p_source.builtin_type;
		if (!valid && p_allow_implicit_conversion) {
			valid = Variant::can_convert_strict(p_source.builtin_type, p_target.builtin_type);
		}
		if (!valid && p_target.builtin_type == Variant::INT && p_source.kind == GDScriptParser::DataType::ENUM && !p_source.is_meta_type) {
			
			valid = true;
		}
		if (valid && p_target.builtin_type == Variant::ARRAY && p_source.builtin_type == Variant::ARRAY) {
			
			if (p_target.has_container_element_type() && p_source.has_container_element_type()) {
				valid = p_target.get_container_element_type() == p_source.get_container_element_type();
			}
		}
		return valid;
	}
	if (p_target.kind == GDScriptParser::DataType::ENUM) {