Investigate the possibility of removing "unlabeled" as a kind of module in the EventSetup system. If it seems like a good idea, remove "unlabeled" from the Framework code and documentation.

"unlabeled" is a remnant left over from the configuration language CMS used before 2008. We believe "unlabeled" was left in the internal Framework implementation because it was needed in the temporary period while both configuration languages were supported. No one remembers this very well as the transition occurred more than 15 years ago. Maybe there is another reason we left this around that we are forgetting about.

This is something mostly internal to the Framework and of low priority. It is an unexpected thing Framework developers need to remember and sometime accommodate when we develop new code in the EventSetup system. It makes the code more complex and difficult to understand. It is also error prone, because we forget this sometimes (see #46484).