[cassandra] Use authenticated connections

In order to use different level of accesses (R/O, R/W) we need to disable the unauthenticated access to cassandra and add dedicated user per workload type

Link to the documentation: https://cassandra.apache.org/doc/latest/cassandra/operating/security.html

• Improve swh-storage to support cassandra authentication provider (#4864 (closed))
• Allow to configure the authentication provider in the helm chart
• Configure the staging environment to use an authentication provider
• Configure cassandra to only allow authenticated connection
  • create a superuser
  • create a read/write user (swh-rw)
  • create a read/only user for internal r/o storage (swh-ro)
  • create a read/only user for human access (guest/guest)