### 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
super(VaultCLI, self).run()
        loader = DataLoader()
        
        old_umask = os.umask(0o077)
        vault_ids = list(context.CLIARGS['vault_ids'])
        
        
        
        
        default_vault_ids = C.DEFAULT_VAULT_IDENTITY_LIST
        vault_ids = default_vault_ids + vault_ids
        action = context.CLIARGS['action']
        
        
        if action in ['decrypt', 'view', 'rekey', 'edit']:
            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'])
            if not vault_secrets: