### Godot version

v4.0.3.stable.official [5222a99f5]
Master [6101240231600c871f5c5473872532c68ea3268c] (confirmed by https://github.com/godotengine/godot/issues/77666#issuecomment-1568952502)

### System information

Window 10

### Issue description

References are not unreferenced at the end of `if` scopes.

### Steps to reproduce

Copy, paste and run the snippet below, check the results:

```gdscript
extends Node


func _ready() -> void:
  var ref := RefCounted.new()
  var ref_count : int

  # OK
  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)

  # OK
  if true:
    var temp := ref
    temp = null

  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)

  # FAIL
  if true:
    var temp := ref

  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)
```

Output example:

```
Expected: 1, Result: 1
Expected: 1, Result: 1
Expected: 1, Result: 2
```

### Minimal reproduction project

N/A
set_last_completion_call_arg(argument_index++);
			ExpressionNode *argument = parse_expression(false);
			if (argument == nullptr) {
				push_error("Expected expression as the annotation argument.");
				valid = false;
				continue;
			}
			annotation->arguments.push_back(argument);
		} while (match(GDScriptTokenizer::Token::COMMA) && !is_at_end());
		pop_multiline();
		consume(GDScriptTokenizer::Token::PARENTHESIS_CLOSE, R"*(Expected ")" after annotation arguments.)*");
		pop_completion_call();
	}
	complete_extents(annotation);
	match(GDScriptTokenizer::Token::NEWLINE); 
	if (valid) {
		valid = validate_annotation_arguments(annotation);
	}
	return valid ? annotation : nullptr;
}
void GDScriptParser::clear_unused_annotations() {
	for (const AnnotationNode *annotation : annotation_stack) {
		push_error(vformat(R"(Annotation "%s" does not precede a valid target, so it will have no effect.)", annotation->name), annotation);
	}
	annotation_stack.clear();
}
bool GDScriptParser::register_annotation(const MethodInfo &p_info, uint32_t p_target_kinds, AnnotationAction p_apply, const Vector<Variant> &p_default_arguments, bool p_is_vararg) {
	ERR_FAIL_COND_V_MSG(valid_annotations.has(p_info.name), false, vformat(R"(Annotation "%s" already registered.)", p_info.name));
	AnnotationInfo new_annotation;
	new_annotation.info = p_info;