Aolin

disable switch to import mode for global sort, and add tikv-worker-url config

2

### First-time contributors' checklist - [ ] I've signed [**Contributor License Agreement**](https://cla-assistant.io/pingcap/docs) that's required for repo owners to accept my contribution. ### What is changed, added or deleted? (Required) ###...

charset: update deal with invalid utf8 characters

3

### What is changed, added or deleted? (Required) https://github.com/pingcap/tidb/pull/61972 changed the behaviour of deal with invalid utf8 characters, we should update related docs. ### Which TiDB version(s) do your changes...