Final refactor/cleanup of onboarding progress after move to ee

• Final look around after finishing all onboarding progress movements to ee to see if anything else needs followed up on or refactored/polished further. Final checkout before closing the epic
• Perform final sidekick worker cleanup for deprecated workers with comment in code with this issue url - https://docs.gitlab.com/ee/development/sidekiq/compatibility_across_updates.html#in-a-subsequent-separate-minor-release