ci(framework) Optimize Ubuntu base image

[Robert-Steiner]

Issue

Description

• Optimizes the Ubuntu base image.
  • Uses python-build (a pyenv plugin) to install Python. That makes the pyenv rehash call obsolete. 🎉
  • Adds a non-root app user.
  • Uses a multi-stage build to avoid having system dependencies in the final base image that are necessary for Python compilation.
  • Use a virtual environment to ensure that Python packages are installed in the same location regardless of whether the subsequent image build is run with the app or the root user (also applies for the Alpine base image).
• Increases the CI timeout to 180 min because the compilation of grpcio on alpine arm64 takes over two hours.
• Adds the Alpine base image to the build CI job.
• Adjusts the Alpine base image to be aligned with the Ubuntu base image (virtual env is under /app/venv).

Related issues/PRs

Proposal

Explanation

Checklist

• Implement proposed change
• Write tests
• Update documentation
• Update the changelog entry below
• Make CI checks pass
• Ping maintainers on Slack (channel #contributions)

Changelog entry

Any other comments?

[tanertopal]

lgtm!