[Future] More thoroughly remove unused components

[jefferya]

Currently, the leaf-bagger is built upon a layer adds the possibility to use an Nginx/FPM app with islandora-Bagger. If a decision is made to adopt the currently hastily implemented approach then the following should be done

• more thoroughly remove Nginx and FPM from the image (perhaps using a different base OCI image without)
  • Remove unused components nginx & fpm from startup #6 temporarily removes from s6-overlay startup
• create a separate user to run the crontab, leaf-bagger applications plus store files
  • add a migration plan