Issue: Health Checks Continue Running After Provider Closure

[ggivo]

Problem: When MultiClusterPooledConnectionProvider.close() was called, the health check threads continued running in the background because the HealthStatusManager and its underlying HealthCheckCollection were not being properly shut down. This caused resource leaks with background threads continuing to execute health checks against Redis endpoints even after the connection provider was closed.

[ggivo]

Closed with #4252