Enable create_if_not_exists, check_not_exists, remove_recursive feature flags

Why it matters

The feature flags enable additional Keeper requests that improve ZooKeeper compatibility and management capabilities in ClickHouse's Keeper service. Enabling them by default simplifies configuration and enhances functionality by supporting operations like conditional creation, existence checks, and recursive node removal.

How to use it

These feature flags are now enabled by default in Keeper. Users do not need to manually enable them to utilize the new request types. To leverage these features, use Keeper requests that correspond to create_if_not_exists, check_not_exists, and remove_recursive operations during coordination tasks.