[Build] Define k8-agent for linux.x86_64 natives completely in pipeline

[HannesWell]

This avoids the need to use customized docker images maintained in eclipse.platform.releng.aggregator.

This is similar to eclipse-platform/eclipse.platform.swt#1332.

[github-actions]

Test Results

  660 files  ±0    660 suites  ±0   1h 13m 23s ⏱️ - 2m 3s
2 195 tests ±0  2 148 ✅ ±0   47 💤 ±0  0 ❌ ±0 
6 729 runs  ±0  6 586 ✅ ±0  143 💤 ±0  0 ❌ ±0 

Results for commit 4f89a2f. ± Comparison against base commit f582f10.

♻️ This comment has been updated with latest results.

[HannesWell]

Looks like we can't install the GTK development packages using yum -y install gtk3-devel since it requires elevated permissions.
Using sudo yum -y install gtk3-devel also does not work since it says sudo is unknown. Furthermore the specifying the container with privileged: true is also not permitted.

I also thought about levering nested-pod-templates but I didn't found a docker image for GTK development (on centos), that is not one of the ones we build our-self in releng.aggregator (and I actually would like to get rid of).

@akurtakov any idea how to solve this?

In the end I would like to define in something in this repo, ideally in the Jenkins pipeline, what needs to be installed in the container on top of the eclipsecbi/jiro-agent-centos-8 image.

[HannesWell]

Can something like this be a solution?
https://stackoverflow.com/questions/36651091/how-to-install-packages-in-linux-centos-without-root-user-with-automatic-depen

[HannesWell]

The idea of this does not work because docker-images are 'immutable' and one cannot simply install extra software.
So I'm closing this one.

The simplification of the definition was extracted into #671.