[automatic failover] Refine Default behaviour when HealthCheckStrategySupplier is not explicitly provided #3555
Description
Follow-up from discussion in PR #3541.
Clarify and improve how HealthCheckStrategySupplier behaves when not explicitly configured
Prerequisites:
- At least one Default HealthCheckStrategy (PING-based) is already implemented.
Goals:
- implement defaults when “no health checks are expicitly configured”
- Decide if we will support RedisDatabase failvoer/failback without health check's (CB only)