Support removing data from Cassandra storage

swh alter remove should support removing data from Cassandra storage.

changed milestone to %Tooling for takedown notices [Roadmap - Collect]

added activity::Implementation label

assigned to @lunar

unassigned @lunar

mentioned in issue swh/infra/sysadm-environment#5046 (closed)

mentioned in issue swh/meta#4803 (closed)

mentioned in merge request swh-storage!1086 (merged)

mentioned in commit swh-storage@1558a646

This is supported by swh-alter v0.0.3.

closed