### 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)

Variant result = Variant();
	if (p_variable->initializer) {
		bool is_initializer_value_reduced = false;
		Variant initializer_value = make_expression_reduced_value(p_variable->initializer, is_initializer_value_reduced);
		if (is_initializer_value_reduced) {
			result = initializer_value;
		}
	} else {
		GDScriptParser::DataType datatype = p_variable->get_datatype();
		if (datatype.is_hard_type()) {
			if (datatype.kind == GDScriptParser::DataType::BUILTIN && datatype.builtin_type != Variant::OBJECT) {
				if (datatype.builtin_type == Variant::ARRAY && datatype.has_container_element_type()) {
					result = make_array_from_element_datatype(datatype.get_container_element_type());
				} else {
					VariantInternal::initialize(&result, datatype.builtin_type);
				}
			} else if (datatype.kind == GDScriptParser::DataType::ENUM) {
				result = 0;
			}
		}
	}
	return result;
}
GDScriptParser::DataType GDScriptAnalyzer::type_from_variant(const Variant &p_value, const GDScriptParser::Node *p_source) {