Remove legacy Castellan jobs
Needed-by:
- periodic-ocata
- periodic-pike
- publish-to-pypi
- check:
- jobs:
- - legacy-castellan-dsvm-functional
- gate:
- jobs:
- - legacy-castellan-dsvm-functional
experimental:
jobs:
- legacy-barbican-simple-crypto-dsvm-tempest-castellan-from-git:
