Allows us to speed up calls to bundler by specifying groups to operate on.

(MAINT) Group gem dependencies

 - Reduce both the start period by 2m and increase the retries
   by 1m to overall reduce wait time from 6m to 5m

 - This time only needs to be longer than Postgres, which has a
   healthcheck timeout defined in docker-compose (given its the
   stock container), but which typically starts under LCOW in
   about 2m

   Additional time allotted is to cover migrations

 - Restructure the scripted waiter to wait in the correct order for
   services (matching pe-puppetdb), and also to ensure that it roughly
   considers time already elapsed, rather than continually adding time.

   Even though SSL is not enabled here, the order is kept the same as
   pe-puppetdb for consistency:

   puppetserver
   postgres

   Once Postgres is up, this container can start!