Allow disabling of PSI__ async metrics collection

Why it matters

This feature addresses the need to control the overhead caused by collecting PSI__ async metrics. By allowing users to disable this collection, it helps optimize performance and resource usage in environments where these metrics are not required.

How to use it

Users can disable the asynchronous collection of PSI__ metrics by configuring the appropriate setting in the ClickHouse configuration file or runtime parameters. This allows turning off these metrics collection without affecting other operations.