### Summary

Using docker_container_exec's stdin syntax doesn't decrypt vaulted variables.

I was suggested in https://github.com/ansible-collections/community.docker/issues/241 that it's most likely issue with Ansible, not the collection.

### Issue Type

Bug Report

### Component Name

docker_container_exec

### Ansible Version

```console
$ ansible --version
ansible [core 2.11.6]
  python version = 3.9.7 (default, Sep 10 2021, 14:59:43) [GCC 11.2.0]
  jinja version = 3.0.3
  libyaml = True
```


### Configuration

```console
$ ansible-config dump --only-changed
ANSIBLE_NOCOWS(/home/user/.ansible.cfg) = True
CACHE_PLUGIN(/home/user/.ansible.cfg) = jsonfile
CACHE_PLUGIN_CONNECTION(/home/user/.ansible.cfg) = /tmp/ansible-cachedir
CACHE_PLUGIN_TIMEOUT(/home/user/.ansible.cfg) = 5
DEFAULT_GATHERING(/home/user/.ansible.cfg) = smart
DEPRECATION_WARNINGS(/home/user/.ansible.cfg) = False
DIFF_ALWAYS(/home/user/.ansible.cfg) = True
HOST_KEY_CHECKING(/home/user/.ansible.cfg) = False
```


### OS / Environment

- Target: Ubuntu 20.04.3

### Steps to Reproduce

```yaml
    - name: Upload key
      community.docker.docker_container_exec:
        argv:
          - tee
          - secret.json
        container: '{{ docker_id }}'
        stdin: '{{ secret_data | to_json }}'
```

Var file (vaulted value is embedded):

```
secret_data:
  priv_key:
    value: !vault |
        $ANSIBLE_VAULT;1.1;AES256
        1161...
        ....
  pub_key:
    value: some_public_key
```

### Expected Results

Vaulted variable is properly decrypted.

I've tested encryption with:

```
ansible localhost -m ansible.builtin.debug -a var=secret_data -e @all/vars.yml
```

and the syntax is valid (variable is decrypted as expected), but not when using docker collection.

### Actual Results

```console
JSON file which was created consist ansible vault data, not decrypted string.

 below
"value": {"__ansible_vault": "$ANSIBLE_VAULT;1.1;AES256;\n1161...
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
''' return its argument quoted for shell usage '''
    if a is None:
        a = u''
    return shlex.quote(to_text(a))
def fileglob(pathname):
    ''' return list of matched regular files for glob '''
    return [g for g in glob.glob(pathname) if os.path.isfile(g)]
def regex_replace(value='', pattern='', replacement='', ignorecase=False, multiline=False):
    ''' Perform a `re.sub` returning a string '''
    value = to_text(value, errors='surrogate_or_strict', nonstring='simplerepr')
    flags = 0
    if ignorecase:
        flags |= re.I
    if multiline:
        flags |= re.M
    _re = re.compile(pattern, flags=flags)
    return _re.sub(replacement, value)
def regex_findall(value, regex, multiline=False, ignorecase=False):
    ''' Perform re.findall and return the list of matches '''
    value = to_text(value, errors='surrogate_or_strict', nonstring='simplerepr')
    flags = 0
    if ignorecase:
        flags |= re.I
    if multiline:
        flags |= re.M
    return re.findall(regex, value, flags)
def regex_search(value, regex, *args, **kwargs):