### 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
if (err) {
					return err;
				}
				if (if_n->false_block) {
					gen->write_else();
					err = _parse_block(codegen, if_n->false_block);
					if (err) {
						return err;
					}
				}
				gen->write_endif();
			} break;
			case GDScriptParser::Node::FOR: {
				const GDScriptParser::ForNode *for_n = static_cast<const GDScriptParser::ForNode *>(s);
				codegen.start_block();
				GDScriptCodeGenerator::Address iterator = codegen.add_local(for_n->variable->name, _gdtype_from_datatype(for_n->variable->get_datatype(), codegen.script));
				gen->start_for(iterator.type, _gdtype_from_datatype(for_n->list->get_datatype(), codegen.script));
				GDScriptCodeGenerator::Address list = _parse_expression(codegen, err, for_n->list);
				if (err) {
					return err;
				}
				gen->write_for_assignment(iterator, list);
				if (list.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					codegen.generator->pop_temporary();
				}
				gen->write_for();
				err = _parse_block(codegen, for_n->loop);
				if (err) {
					return err;
				}