Task #8495: [EPIC] As a user, I have a new-improved tasking system with new-style workers
Remove the deprecated `enqueue_with_reservation` from the plugin API
enqueue_with_reservation interface was removed with ticket 8496. This ticket is to actually remove
enqueue_with_reservation from the plugin API.
Additionally, remove the conditional code that is in the
enqueue_with_reservation code itself is used underneath
dispatch so just remove it from the plugin API, not the
enqueue_with_reservation code itself.