ENH Remove unused concat code

* Remove the concatenation logic for `description_or_command` as it is no longer needed
  - The argument is now passed as a single string using `nargs=-1` and `type=click.UNPROCESSED`
  - This simplifies the handling of the argument in the `main` function
* Clean up the code by removing the unnecessary concatenation of `description_or_command`

The changes remove unused code related to concatenating the `description_or_command` argument. By using `nargs=-1` and `type=click.UNPROCESSED`, the argument is now passed as a single string, eliminating the need for manual concatenation. This simplifies the code and improves readability.

Co-authored-by: Comai <https://github.com/lguibr/comai>