Remove stores that have been pruned during the detection #52313
Description
Enhancement
Before sending mpp tasks, tidb will detect the liveness of tiflash nodes. However, tidb also detect nodes that have been pruned from the cluster. Once the detection of one tiflash node fails. The failed tiflash node will be added to a list to be periodically detected. If many tiflash nodes have been pruned before, the number of detection request will be very large and affects the network of production environment. So we need to detect nodes that are valid in the cluster.