[hibernate-dev] Keeping CI from being confusing.

I see many jobs are still explicitly configured to request a build on slaves tagged as "OS1". Please get rid of that: we have no longer any slave running on OS1, some of the new slaves use the "OS1" label to allow a smooth migration - but it's a lie and it's been a long time since we removed OS1. I will need to eventually cleanup such things, as it's getting messy and confusing. Labels are expected to be used to tag specific slaves to have specific capabilities, so that some jobs can flag they require such capabilities. Typically the only label you need is "Slave" as we don't want most jobs to run on the master node. An example of a valid label is "HANA" for the job running integration tests on the HANA database; for obvious reasons this job needs to be run on the only slave actually having HANA running. While at it, if you installed any Jenkins plugin which you no longer need please remove it. General reminder: there's no dedicated team to keep CI or infrastructure running efficiently, we're all responsible so try to dedicate it some 20 minutes every month making sure your jobs are still necessary and configurations are up to date. For more extensive operations ask Davide or myself and we'll see to help. Thanks, Sanne