Improvements

• Make the scheduling results of the scatter-range-scheduler scheduler more even by allowing the scheduler to schedule empty Regions and fix the configurations of the scheduler #4497

Bug fixes

• Fix the issue that operator can get blocked due to down store #3353
• Fix the issue that the speed of removing peers is limited when repairing the down nodes #4090
• Fix the issue that the hotspot cache cannot be cleared when the Region heartbeat is less than 60 seconds #4390