docker/DockerFile: Bump jenkins image from jdk11 to lts-jdk17
The Jenkins instance located at jenkins.softwareheritage.org now uses java 17 so align the base docker image used to test jenkins jobs changes accordingly.
Staging instance, all changes can be removed at any time
The Jenkins instance located at jenkins.softwareheritage.org now uses java 17 so align the base docker image used to test jenkins jobs changes accordingly.