"Comments per page" setting cannot be configured to "all comments"

Problem/Motivation

"Comments per page" setting cannot be configured to show "all comments" also if the dockbook of CommentStorageInterface::loadThread says:

   * @param int $comments_per_page
   *   (optional) The amount of comments to display per page.
   *   Defaults to 0, which means show all comments.

I can't set 0 for "Comments per page" due to hardcoded "min" on form element (introduced with #2239369: "Comments per page" setting cannot be configured to be larger than 300 and modified with #2906298: Comments per page number validation)

Proposed resolution

I think we could set "min" as 0 for permit to show all comments without pager.

In the next comment the patches for 8.7.x and 8.5.x