Adjust Sidekiq recommendations for 5k and less Reference Architectures

What does this MR do?

Sidekiq is a very elastic component and its demands can vary notably depending on usage shape due to its queue like nature. By separating it into its own nodes it allows for much more flexibility for adjusting it without also having to impact rails. This is the case for all RAs except the 2k, where it lives with Rails and in turn will require Rails to also be scaled up if required.

Based on above the changes are the following:

• 2k - Separate Sidekiq out of Rails into it's own box (1 4 vCPU).
• 3k - Switch from 4 2 vCPU to 2 4 vCPU boxes to reduce maintenance overhead.
• 5k - Switch from 4 2 vCPU to 2 4 vCPU boxes to reduce maintenance overhead.

Note: If a customer is running on an Reference Architecture today with no issues then there are no changes here that will apply to them. These adjustments are for existing customers where the environment is not performant for their use case and of course for new incoming customers.

Related issues

Adjust Sidekiq recommendations for 5k and less ... (gitlab-org/quality/reference-architectures#232 - closed)

Author's checklist

• Follow the:
  • Documentation process.
  • Documentation guidelines.
  • Style Guide.
• If you're adding or changing the main heading of the page (H1), ensure that the product tier badge is added.
• If you are a GitLab team member, request a review based on:
  • The documentation page's metadata.
  • The associated Technical Writer.

If you are a GitLab team member and only adding documentation, do not add any of the following labels:

• ~"frontend"
• ~"backend"
• ~"type::bug"
• ~"database"

These labels cause the MR to be added to code verification QA issues.

Reviewer's checklist

Documentation-related MRs should be reviewed by a Technical Writer for a non-blocking review, based on Documentation Guidelines and the Style Guide.

If you aren't sure which tech writer to ask, use roulette or ask in the #docs Slack channel.

• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
  • Ensure docs metadata is present and up-to-date.
  • Ensure the appropriate labels are added to this MR.
  • Ensure a release milestone is set.
  • If relevant to this MR, ensure content topic type principles are in use, including:
    • The headings should be something you'd do a Google search for. Instead of Default behavior, say something like Default behavior when you close an issue.
    • The headings (other than the page title) should be active. Instead of Configuring GDK, say something like Configure GDK.
    • Any task steps should be written as a numbered list.
    • If the content still needs to be edited for topic types, you can create a follow-up issue with the docs-technical-debt label.
• Review by assigned maintainer, who can always request/require the reviews above. Maintainer's review can occur before or after a technical writer review.