Fix sleep duration in signal handler functionality

Why it matters

This fix addresses an issue where the sleep invocation inside signal handlers was sleeping for less time than expected, which could lead to improper timing behavior in signal processing. Correcting this ensures signal handlers behave reliably according to the specified sleep durations.

How to use it

No special user action is required. The fix is applied internally and will take effect automatically when handling signals involving sleep calls after updating ClickHouse to the version that includes this change.