After truncating a table in TiDB, the old table's stats meta is not deleted

[hi-rustin]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduction step (Required)

1. Create a table: create table t (c1 int, c2 int)
2. Insert some data: insert into t values (1,2),(2,2),(6,2),(11,2),(16,2)
3. Analyze the table: analyze table t
4. Wait for 20min, Truncate the table t: truncate table t
5. Wait for 15min, check the stats meta again.

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

The old table stats meta gets deleted.

3. What did you see instead (Required)

It still exists in the table.

4. What is your TiDB version? (Required)

master