Improve tests for cta-change-storage-class and cta-restore-deleted-files

Authentication in these tests are wrong. Instead of specifying sss in the environment variables, they should use kerberos. Use

XrdSecPROTOCOL=krb5 KRB5CCNAME=/<path>/ctaadmin2/krb5cc_0

instead of

XrdSecPROTOCOL=sss XrdSecSSSKT=/etc/cta/eos.sss.keytab

The correct admin key must be placed on the frontend pod.