[java] Fix buildpack lib-injection image

[randomanderson]

Motivation

Multiple issues with the buildpack image meant it always failed. These failures went unnoticed because the test is marked as flaky.

Changes

Fixes were:

• Using the docker.io proxy for the buildpacks
• Copying the correct docker-compose file
• Starting the docker daemon
• Removing flaky markers

Reviewer checklist

• If PR title starts with [<language>], double-check that only <language> is impacted by the change
• No system-tests internal is modified. Otherwise, I have the approval from R&P team
• CI is green, or failing jobs are not related to this change (and you are 100% sure about this statement)
• A docker base image is modified?
  • the relevant build-XXX-image label is present
• A scenario is added (or removed)?
  • Get a review from R&P team