### 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)

StringName function_name = p_call->function_name;
		Variant::Type builtin_type = GDScriptParser::get_builtin_type(function_name);
		if (builtin_type < Variant::VARIANT_MAX) {
			
			call_type.type_source = GDScriptParser::DataType::ANNOTATED_EXPLICIT;
			call_type.kind = GDScriptParser::DataType::BUILTIN;
			call_type.builtin_type = builtin_type;
			if (builtin_type == Variant::OBJECT) {
				call_type.kind = GDScriptParser::DataType::NATIVE;
				call_type.native_type = function_name; 
			}
			bool safe_to_fold = true;
			switch (builtin_type) {
				
				
				case Variant::OBJECT:
				case Variant::DICTIONARY:
				case Variant::ARRAY:
				case Variant::PACKED_BYTE_ARRAY:
				case Variant::PACKED_INT32_ARRAY:
				case Variant::PACKED_INT64_ARRAY:
				case Variant::PACKED_FLOAT32_ARRAY:
				case Variant::PACKED_FLOAT64_ARRAY:
				case Variant::PACKED_STRING_ARRAY:
				case Variant::PACKED_VECTOR2_ARRAY:
				case Variant::PACKED_VECTOR3_ARRAY:
				case Variant::PACKED_COLOR_ARRAY:
					safe_to_fold = false;
					break;
				default: