Fix Memory Leak from Zookeeper Exists Watch

Why it matters

This fix addresses a memory management issue where watches set on ZooKeeper nodes with the exists command could lead to memory leaks. By resolving this, the system's stability and resource usage improve, preventing unnecessary memory consumption during ZooKeeper interactions.

How to use it

This fix is applied internally within ClickHouse. Users should upgrade to the ClickHouse version that includes this fix to benefit from the resolved memory leak. No additional configuration or user action is required.