Write data in the e2e tests

[burmanm]

What is missing? Most of our operations in the e2e tests act against empty Cassandra nodes. We should create a schema and write some data to them to ensure that they function correctly.

We don't need to write a lot of data (GHA constraints and to prevent slowing down the tests too much), but even a small amount of "user-generated" is enough to ensure the cluster is actually working.

Why do we need it? Operations such as cleanup / rebuild have no effect if there's nothing to cleanup or rebuild. Or replication changes.

┆Issue is synchronized with this Jira Story by Unito ┆Issue Number: CASS-51