[FLOSS H2] Upgrade Jenkins node to Debian bullseye

[0x6178656c]

Since the CMake version is now incompatible with the one from the Debian stretch repository, I upgraded the Dockerfile to use Debian bullseye.

The only change in packages was:

• openjdk-8-jdk-headless to openjdk-11-jdk-headless

I successfully ran

run-make-env

in the container.

Basics

• Short descriptions of your changes are in the release notes
  (added as entry in doc/news/_preparation_next_release.md which
  contains _(my name)_)
  Please always add something to the release notes.
• Details of what you changed are in commit messages
  (first line should have module: short statement syntax)
• References to issues, e.g. close #X, are in the commit messages.
• The buildservers are happy. If not, fix in this order:
  • add a line in doc/news/_preparation_next_release.md
  • reformat the code with scripts/dev/reformat-all
  • make all unit tests pass
  • fix all memleaks
• The PR is rebased with current master.

Checklist

• I added unit tests for my code
• I fully described what my PR does in the documentation
  (not in the PR description)
• I fixed all affected documentation (see Documentation Guidelines)
• I added code comments, logging, and assertions as appropriate (see Coding Guidelines)
• I updated all meta data (e.g. README.md of plugins and METADATA.ini)
• I mentioned every code not directly written by me in reuse syntax

Review

• Documentation is introductory, concise, good to read and describes everything what the PR does
• Examples are well chosen and understandable
• Code is conforming to our Coding Guidelines
• APIs are conforming to our Design Guidelines
• Code is consistent to our Design Decisions

Labels

• Add the "work in progress" label if you do not want the PR to be reviewed yet.
• Add the "ready to merge" label if the basics are fulfilled and no further pushes are planned by you.

[markus2330]

Thank you for the PR, great job! Can you please also update scripts/docker/jenkinsnode/README.md

The README.md needs some overhaul, it is not confirming to the Documentation Guidelines.

@lukashartl can you verify if this is still used or compatible with our Ansible setup of agents?

[0x6178656c]

Thank you for the PR, great job! Can you please also update scripts/docker/jenkinsnode/README.md

The README.md needs some overhaul, it is not confirming to the Documentation Guidelines.

@lukashartl can you verify if this is still used or compatible with our Ansible setup of agents?

I read the documentation on the build process and it is actually not clear to me if this Docker image is still used at all?

The documentation states that the Jenkins nodes should have Docker installed, but this is not the case for this image.
https://github.com/ElektraInitiative/libelektra/blob/master/doc/BUILDSERVER.md#adding-a-jenkins-node

I propose the following:

• If this image is still relevant this should be documented accordingly
• If this image is no longer used it should be removed from repository

[lukashartl]

@markus2330

@lukashartl can you verify if this is still used or compatible with our Ansible setup of agents?

It is not used for our main build agents. Those are already on bullseye and are using jdk 11. (ansible is also enforcing jdk 11)

I honestly don't know if anyone is still using this image?

[markus2330]

Thank you for the update&testing!

I propose the following:

I agree, I created #4637.