drop jenkins-build script as the entire jobs are versioned now
let japi beautify job configs when fetching to have consistent diffs

It is necessary to beautify the xml as the xml output of jenkins api
and the output of libXML differ slightly. So we take the output
of libXML to prevent useless diffs and be able to automatically edit
the configs with via scripts (with libXML).
allow trackupstream script to edit the jenkins job config directly

The cloud-trackupstream-matrix script can now directly modify the
fetched jobs (fetched via japi). It replaces the axis configuration
and the combination filter (a groovy script). All these are dynamically
generated from its internal config hash.

We (only) change this hash according to our needs.
The workflow is:
- change the hash according to our needs and create a git commit
- fetch job (via japi)
- if there is a diff, create a new git commit
- let cloud-trackupstream-matrix.pl adapt the job
- create a new git commit
- push job (via japi)