debusine-worker configuration file `log-level` is ignored

debusine-worker configuration file log-level is ignored.

In debusine/worker/__main__.py there is:

    parser.add_argument(
        '--log-level',
        help='Minimum log level. Overrides log-level (in '
        '[General] section) from config.ini.',
        choices=['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'],
        default='INFO',
    )

the default='INFO' and Worker.__init__ uses the default (named "original" there) instead of using the one from the configuration file.

Worker._setup_logging assumes that the command line has higher precedence than the config file level. But the user didn't pass INFO in the command line, it was the default one.