##### 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
```


#
#
#
#
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import os
import ansible.constants as C
from ansible.errors import AnsibleParserError, AnsibleAssertionError
from ansible.module_utils._text import to_bytes
from ansible.module_utils.six import iteritems, string_types
from ansible.parsing.splitter import split_args, parse_kv
from ansible.parsing.yaml.objects import AnsibleBaseYAMLObject, AnsibleMapping
from ansible.playbook.attribute import FieldAttribute
from ansible.playbook.base import Base
from ansible.playbook.conditional import Conditional
from ansible.playbook.taggable import Taggable
from ansible.utils.collection_loader import AnsibleCollectionConfig
from ansible.utils.collection_loader._collection_finder import _get_collection_name_from_path, _get_collection_playbook_path
from ansible.template import Templar
from ansible.utils.display import Display
display = Display()
class PlaybookInclude(Base, Conditional, Taggable):
    _import_playbook = FieldAttribute(isa='string')
    _vars = FieldAttribute(isa='dict', default=dict)
    @staticmethod
    def load(data, basedir, variable_manager=None, loader=None):
        return PlaybookInclude().load_data(ds=data, basedir=basedir, variable_manager=variable_manager, loader=loader)
    def load_data(self, ds, basedir, variable_manager=None, loader=None):