##### SUMMARY
The PR https://github.com/ansible/ansible/pull/64156 deprecated passing extra variables on `import_playbook`, which was wrongly stated to have never worked before, but it does, as shown in the example below.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
- `import_playbook`

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.10.3
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/goetz/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.8/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.8.6 (default, Sep 30 2020, 04:00:38) [GCC 10.2.0]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
[no output]
```

##### OS / ENVIRONMENT
- GNU/Linux

##### STEPS TO REPRODUCE
`playbooks/site.yaml`:
```yaml
---
- hosts: "{{ target }}"
  roles:
    - role: my-role
```

`playbooks/dev.yaml`:
```yaml
---
- import_playbook: site.yml target='dev'
```

```sh
ansible-playbook playbooks/dev.yml
```

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
Playbook runs without warnings or errors.

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->
Playbooks shows a Warning about this behavior going to fail in a future Ansible minor version update.
```sh
[WARNING]: Additional parameters in import_playbook statements are not supported. This will be an error in version 2.14
```


if playbook_collection:
            
            AnsibleCollectionConfig.default_collection = playbook_collection
        else:
            
            AnsibleCollectionConfig.playbook_paths.append(os.path.dirname(os.path.abspath(to_bytes(playbook, errors='surrogate_or_strict'))))
        pb._load_playbook_data(file_name=playbook, variable_manager=variable_manager, vars=self.vars.copy())
        
        
        for entry in pb._entries:
            
            if new_obj.when and isinstance(entry, Play):
                entry._included_conditional = new_obj.when[:]
            temp_vars = entry.vars.copy()
            temp_vars.update(new_obj.vars)
            param_tags = temp_vars.pop('tags', None)
            if param_tags is not None:
                entry.tags.extend(param_tags.split(','))
            entry.vars = temp_vars
            entry.tags = list(set(entry.tags).union(new_obj.tags))
            if entry._included_path is None:
                entry._included_path = os.path.dirname(playbook)
            
            
            
            if new_obj.when:
                for task_block in (entry.pre_tasks + entry.roles + entry.tasks + entry.post_tasks):
                    task_block._attributes['when'] = new_obj.when[:] + task_block.when[:]
        return pb
    def preprocess_data(self, ds):