### Godot version

4.1.1

### System information

linux

### Issue description

The `"%+f"` format adds a `+` sign in front of positive numbers. If you try to format `-0.0`, it breaks and displays both a `+` and a `-`.

### Steps to reproduce

```gdscript
@tool
extends EditorScript

func _run() -> void:
    print("%+f" % -0.0)
```

### Minimal reproduction project

see above
s = *this;
	int end = s.find(".");
	if (end == -1) {
		end = s.length();
	}
	if (end == 0) {
		return s;
	}
	int begin = 0;
	while (begin < end && !is_digit(s[begin])) {
		begin++;
	}
	int zeros_to_add = p_digits - (end - begin);
	if (zeros_to_add <= 0) {
		return s;
	} else {
		return s.insert(begin, ("0").repeat(zeros_to_add));
	}
}
 ::trim_prefix(const  &p_prefix) const {