kvnemesis: use ReplicationManual

**Describe the problem**

In https://github.com/cockroachdb/cockroach/pull/89477, TestKVNemesisMultiNode was (accidentally) switched to use ReplicationAuto instead of ReplicationManual, meaning that the TestCluster will upreplicate and also have the replicate queue active throughout the run.

We should decide whether that's desirable and if not, undo this change.

kvnemesis does perform manual replication changes, so manual seems preferrable to preserve as much determinism as possible.

kvnemesis also performs random zone config changes, which I thought was an argument for keeping the replicate queue active, but it turns out that at the time of writing, the only zone cfg change it can make is toggling global reads, which is independent of the replicate queue being active:

https://github.com/cockroachdb/cockroach/blob/97054a0e76049cd8f78d8b534ab1e2107be9f2ed/pkg/kv/kvnemesis/generator.go#L914-L916

Jira issue: CRDB-22630