### Description

Currently, the `airflow variables export` command requires an explicit file path and does not support output to stdout. However connections can be printed to stdout using `airflow connections export -`. This inconsistency between the two export commands can lead to confusion and limits the flexibility of the variables export command.

### Use case/motivation

To bring some consistency, similar to connections, variables should also be printed to STDOUT, using `-` instead of filename. 

### Related issues

_No response_

### Are you willing to submit a PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

schema=args.conn_schema,
            port=args.conn_port,
        )
        if args.conn_extra is not None:
            new_conn.set_extra(args.conn_extra)
    with create_session() as session:
        if not session.scalar(select(Connection).where(Connection.conn_id == new_conn.conn_id).limit(1)):
            session.add(new_conn)
            msg = "Successfully added `conn_id`={conn_id} : {uri}"
            msg = msg.format(
                conn_id=new_conn.conn_id,
                uri=args.conn_uri
                or urlunsplit(
                    (
                        new_conn.conn_type,
                        f"{new_conn.login or ''}:{'******' if new_conn.password else ''}"
                        f"@{new_conn.host or ''}:{new_conn.port or ''}",
                        new_conn.schema or "",
                        "",
                        "",
                    )
                ),
            )
            print(msg)
        else:
            msg = f"A connection with `conn_id`={new_conn.conn_id} already exists."
            raise SystemExit(msg)
@cli_utils.action_cli
@providers_configuration_loaded
def connections_delete(args):