change bugzilla role classes

in preparation for the upcoming switch to new server
and after having merged the new module

kaulen becomes role::bugzilla::old while it's still up,
zirconium uses role::bugzilla with the new module

this way they cant interfere and i'm gonna delete all the
remnants after the full switch

Change-Id: Ica558e2669a8c6949229f592f1c97080df34994f