Scatter region should check success status

[rleungx]

Bug Report

For BR or using the tidb_scatter_region variable, we need to check the success status of the scatter operator. When we create a table, if the region is just splitted, the size might be the original region's size/n, which could not be less than 1. So PD will regard those regions as non-empty regions. Then they might be filtered by store limit.
But BR and client-go will think the scatter region succeeds since they are not in running status but cancel status.

https://github.com/tikv/tikv/blob/9dc7450ef22abde48e14e61fc16d4f22b137d450/components/raftstore/src/store/fsm/peer.rs#L4030-L4031

BR:

tidb/br/pkg/restore/split.go

Line 209 in 66033d5

ok := string(resp.GetDesc()) != "scatter-region" || resp.GetStatus() != pdpb.OperatorStatus_RUNNING

client-go:
https://github.com/tikv/client-go/blob/8a214402da13d5bdc1ffb1d2726bdbb47f9beb74/tikv/split_region.go#L287
https://github.com/tikv/client-go/blob/8a214402da13d5bdc1ffb1d2726bdbb47f9beb74/tikv/split_region.go#L325

The lightning has already been fixed through #33625.

[mittalrishabh]

I opened a PR tikv/pd#6953

[rleungx]

Also related to tikv/tikv#15326