auto analyze of partition table is not triggered after adding index

[xuyifangreeneyes]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

use test;
create table t (a int, b int) partition by range (a) (PARTITION p0 VALUES LESS THAN (2000), PARTITION p1 VALUES LESS THAN MAXVALUE);
-- insert more than 1000 rows into each partition
analyze table t;
alter table t add index idx(a);
show analyze status; -- observe whether auto analyze is triggered after adding the index

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

Auto analyze is triggered after adding the index.

3. What did you see instead (Required)

Auto analyze is not triggered after adding the index.

4. What is your TiDB version? (Required)

master