Add regex on namespace search POD_CLEANUP_KUBERNETES_NAMESPACES

Possibility to define a regex on namespace search.

ex:

    env:
      - name: POD_CLEANUP_INTERVAL
        value: 1h
      - name: POD_CLEANUP_KUBERNETES_NAMESPACES
        value: my_namespace_prefix* 

Signed-off-by: sebastien.heurtematte sebastien.heurtematte@eclipse-foundation.org