### 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)

ARG_VERBOSE,
            ARG_YES,
            ARG_DB_SKIP_ARCHIVE,
        ),
    ),
    ActionCommand(
        name="export-archived",
        help="Export archived data from the archive tables",
        func=lazy_load_command("airflow.cli.commands.db_command.export_archived"),
        args=(
            ARG_DB_EXPORT_FORMAT,
            ARG_DB_OUTPUT_PATH,
            ARG_DB_DROP_ARCHIVES,
            ARG_DB_TABLES,
            ARG_YES,
        ),
    ),
    ActionCommand(
        name="drop-archived",
        help="Drop archived tables created through the db clean command",
        func=lazy_load_command("airflow.cli.commands.db_command.drop_archived"),
        args=(ARG_DB_TABLES, ARG_YES),
    ),
)
CONNECTIONS_COMMANDS = (
    ActionCommand(
        name="get",
        help="Get a connection",
        func=lazy_load_command("airflow.cli.commands.connection_command.connections_get"),
        args=(ARG_CONN_ID, ARG_COLOR, ARG_OUTPUT, ARG_VERBOSE),