### 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)

break;
			}
			if (all_is_constant && safe_to_fold) {
				
				Vector<const Variant *> args;
				for (int i = 0; i < p_call->arguments.size(); i++) {
					args.push_back(&(p_call->arguments[i]->reduced_value));
				}
				Callable::CallError err;
				Variant value;
				Variant::construct(builtin_type, value, (const Variant **)args.ptr(), args.size(), err);
				switch (err.error) {
					case Callable::CallError::CALL_ERROR_INVALID_ARGUMENT:
						push_error(vformat(R"(Invalid argument for %s constructor: argument %d should be "%s" but is "%s".)", Variant::get_type_name(builtin_type), err.argument + 1,
										   Variant::get_type_name(Variant::Type(err.expected)), p_call->arguments[err.argument]->get_datatype().to_string()),
								p_call->arguments[err.argument]);
						break;
					case Callable::CallError::CALL_ERROR_INVALID_METHOD: {
						String signature = Variant::get_type_name(builtin_type) + "(";
						for (int i = 0; i < p_call->arguments.size(); i++) {
							if (i > 0) {
								signature += ", ";
							}
							signature += p_call->arguments[i]->get_datatype().to_string();
						}
						signature += ")";
						push_error(vformat(R"(No constructor of "%s" matches the signature "%s".)", Variant::get_type_name(builtin_type), signature), p_call->callee);
					} break;
					case Callable::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS:
						push_error(vformat(R"(Too many arguments for %s constructor. Received %d but expected %d.)", Variant::get_type_name(builtin_type), p_call->arguments.size(), err.expected), p_call);