### 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)

p_identifier->set_datatype(type_from_metatype(base));
				p_identifier->is_constant = true;
				p_identifier->reduced_value = base.enum_values[name];
				return;
			}
			
			return;
		} else {
			push_error(R"(Cannot get property from enum value.)", p_identifier);
			return;
		}
	}
	if (base.kind == GDScriptParser::DataType::BUILTIN) {
		if (base.is_meta_type) {
			bool valid = true;
			Variant result = Variant::get_constant_value(base.builtin_type, name, &valid);
			if (valid) {
				p_identifier->is_constant = true;
				p_identifier->reduced_value = result;
				p_identifier->set_datatype(type_from_variant(result, p_identifier));
			} else if (base.is_hard_type()) {
#ifdef SUGGEST_GODOT4_RENAMES
				String rename_hint = String();
				if (GLOBAL_GET(GDScriptWarning::get_settings_path_from_code(GDScriptWarning::Code::RENAMED_IN_GODOT_4_HINT)).booleanize()) {
					const char *renamed_identifier_name = check_for_renamed_identifier(name, p_identifier->type);
					if (renamed_identifier_name) {
						rename_hint = " " + vformat(R"(Did you mean to use "%s"?)", renamed_identifier_name);
					}
				}
				push_error(vformat(R"(Cannot find constant "%s" on base "%s".%s)", name, base.to_string(), rename_hint), p_identifier);