DDL failed with error `failed to create remote duplicate kv stream` when TiKV is unstable

[lance6716]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

when add unique index, restart TiKV or make network unstable

2. What did you expect to see? (Required)

DDL job should retry and succeed

3. What did you see instead (Required)

4. What is your TiDB version? (Required)