### Summary

`ansible-vault encrypt_string --help` shows the `--output` option but it remains without effect.

### Issue Type

Bug Report

### Component Name

ansible-vault

### Ansible Version

```console
$ ansible --version
ansible 2.9.21
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/elavarde/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.9/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.9.5 (default, May 14 2021, 00:00:00) [GCC 11.1.1 20210428 (Red Hat 11.1.1-1)]
```


### Configuration

```console
$ ansible-config dump --only-changed
[... empty ...]
```


### OS / Environment

Fedora 34

### Steps to Reproduce

```shell
ansible-vault encrypt_string --ask-vault-pass --name myvar --output vault.yml 'some secret'
```


### Expected Results

Variable and its encrypted content are written to file and not to stdout _or_ the option `--output` isn't shown in the help.

Making the `--output` version working would probably be a duplicate of issue #59590, so probably removing the `--output` option which doesn't work could be a simpler step. More important for now is that it's consistent.

### Actual Results

```console
- output file isn't created/edited
- variable and its content are output to stdout
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
raise AnsibleOptionsError("A vault password is required to use Ansible's Vault")
        if action in ['encrypt', 'encrypt_string', 'create']:
            encrypt_vault_id = None
            
            if action not in ['edit']:
                encrypt_vault_id = context.CLIARGS['encrypt_vault_id'] or C.DEFAULT_VAULT_ENCRYPT_IDENTITY
            vault_secrets = None
            vault_secrets = \
                self.setup_vault_secrets(loader,
                                         vault_ids=vault_ids,
                                         vault_password_files=list(context.CLIARGS['vault_password_files']),
                                         ask_vault_pass=context.CLIARGS['ask_vault_pass'],
                                         create_new_password=True)
            if len(vault_secrets) > 1 and not encrypt_vault_id:
                raise AnsibleOptionsError("The vault-ids %s are available to encrypt. Specify the vault-id to encrypt with --encrypt-vault-id" %
                                          ','.join([x[0] for x in vault_secrets]))
            if not vault_secrets:
                raise AnsibleOptionsError("A vault password is required to use Ansible's Vault")
            encrypt_secret = match_encrypt_secret(vault_secrets,
                                                  encrypt_vault_id=encrypt_vault_id)
            
            
            self.encrypt_vault_id = encrypt_secret[0]
            self.encrypt_secret = encrypt_secret[1]
        if action in ['rekey']:
            encrypt_vault_id = context.CLIARGS['encrypt_vault_id'] or C.DEFAULT_VAULT_ENCRYPT_IDENTITY