### 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 (p_source.kind == GDScriptParser::DataType::BUILTIN && p_source.builtin_type == Variant::INT) {
#ifdef DEBUG_ENABLED
			if (p_source_node) {
				parser->push_warning(p_source_node, GDScriptWarning::INT_AS_ENUM_WITHOUT_CAST);
			}
#endif
			return true;
		}
		if (p_source.kind == GDScriptParser::DataType::ENUM) {
			if (p_source.native_type == p_target.native_type) {
				return true;
			}
		}
		return false;
	}
	
	if (p_source.kind == GDScriptParser::DataType::BUILTIN && p_source.builtin_type == Variant::NIL) {
		
		return true;
	}
	StringName src_native;
	Ref<Script> src_script;
	const GDScriptParser::ClassNode *src_class = nullptr;
	switch (p_source.kind) {
		case GDScriptParser::DataType::NATIVE:
			if (p_target.kind != GDScriptParser::DataType::NATIVE) {
				
				return false;
			}
			if (p_source.is_meta_type) {