Delivered a stability guard for MV tests in the scylla-cluster-tests suite during the tablets feature rollout. Implemented conditional logic in Nemesis to disable Materialized View tests (CreateIndex and AddRemoveMv) when tablets are enabled and scylladb/scylla-enterprise#5461 is open, and to raise UnsupportedNemesis in those cases. This change reduces flaky CI failures and improves overall testing reliability without impeding feature delivery, reinforcing test governance and rollout risk management.

November 2024: Implemented a targeted reliability improvement in cluster upgrade tests by introducing a context manager to suppress intermittent topology change coordinator errors (unavailable_exception and connection is closed) during upgrades in scylla-cluster-tests. This reduces noise from non-critical errors, shortening upgrade cycles, and enabling faster, more reliable upgrade validation in CI. The change integrates cleanly with the existing upgrade workflow and focuses on maintainability for future fixes. Primary commit: 3c8655d22333cb73ae53725e91fc9565f30cbb23.