fix compatibility issues during techlab exec

[fmacheleidt]

fixing issues during techlab execution (jenkins version / plugin compatibility > Dockerfile) (dated rsa would not work after upgrade > ssh-keys.sh) (naming issue for agents > jenkins.yaml) (https://www.jenkins.io/doc/book/security/controller-isolation/jep-235/ > jenkins.yaml)

[github-actions[bot]]

PR Environments:

• puzzle https://jenkins-techlab-pr-299.ocp.cloudscale.puzzle.ch