Replace Thread.Sleep with task.Delay

[alekhyareddy28]

Performance Improvement of PT Run

Similar to PR #7401, replacing Thread.Sleep with Task.Delay throughout the codebase would improve the performance of PT Run as Thread.Sleep blocks the thread that it is called on whereas Task.Delay uses a timer instead and schedules a thread to resume work after the interval has passed. This does not block the thread.

[crutkas]

From the current snapshot in master, here is the offenders