Remove the pre-outputformats old-fashioned 'format' option from config-list command.

Before this change, the help output was:

 --format                                  Define the output format.
 Known formats are: json, print_r, and export. Available: list, json,
 var_export, yaml. Default is list.

 Now it is:

  --format=<json>                           Select output format.
  Available: list, json, var_export, yaml. Default is list.