[tidb-x] tikv leader can not migrate back due to disk throughput limitation resulting in continuous slight disk jitter

## Bug Report

on tidbx cloud env
tikv leader migration is triggered by br restore data (multiple tikv are under high pressure)

04-22 3:25 : tikv leader was evicted at the second time

04-22 3:30：slow score down to 1

04-22 04:00：The leader did not move back

raft disk throughput Exceeded

### What did you expect to see?
the tikv leader can move back after slow score down to 1

### What did you see instead?
after slow score down to 1, tikv leader can not migrate back due to disk throughput limitation resulting in continuous slight disk jitter

### What version of PD are you using (`pd-server -V`)?
release-nextgen.202510.25