Using Kerberos for auth between Galaxy and Pulsar

[martindemko]

Despite the lack of support for this in Galaxy sources, we could still use it. We need to be sure of two things on the Galaxy side:

• There must be a user accessible via a krb ticket, either running Galaxy (galaxy_user) or having access to Galaxy datasets
• This user must be the same as the user running Pulsar and submitting jobs to PBS (as the pulsar user is using krb tickets with Ansible support already)

Both conditions currently apply to all production servers: RE, GCZ , UMSA