Bug Report
Please answer these questions before submitting your issue. Thanks!
1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)
When a table uses the clustered index, it will not have any _tidb_rowid key.
3. What did you see instead (Required)
tidb_decode_key still shows _tidb_rowid content.
4. What is your TiDB version? (Required)
03b6a8e