Draft: Improve unit/integration test start times

What does this MR do?

• Splits up helper image job into two:

  • helper image
  • helper image for ci

• Splits up ${CI_IMAGE} image into two:

  • One used as part of our testing: ${CI_IMAGE}
  • Another for helper image building, packaging and releasing: ${CI_IMAGE}-packaging.

Why was this MR needed?

• Helper images take a while to build. By unit and integration tests depending only on helper image for ci, they now wait half the time.
• Our CI_IMAGE was getting large. Utilities used for packaging and releasing are not needed for testing. Preparing a build environment for tests was taking 48-55s, it is now reduced to 25-34s.

What's the best way to test this MR?

• Ensure pipeline is passing.
• Ensure helper images for ci is finishing faster than previous helper images performing all of the work.
• Check previous unit test jobs to ensure the Preparing the "docker+machine" executor is completing faster.

What are the relevant issue numbers?

Closes #27930 (closed)

Closes #27934