in bdr mode, primary can't execute add implicit nullable column

[okJiang]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

admin set bdr role primary;

mysql> create table t3(b int, f int);
Query OK, 0 rows affected (0.16 sec)
mysql> alter table t3 add column g bigint as (b + f) virtual;
ERROR 8263 (HY000): The operation is not allowed while the bdr role of this cluster is set to primary.
mysql> alter table t3 add column aaa int default 0;
ERROR 8263 (HY000): The operation is not allowed while the bdr role of this cluster is set to primary.

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

execute successfully

3. What did you see instead (Required)

ERROR 8263 (HY000): The operation is not allowed while the bdr role of this cluster is set to primary.

4. What is your TiDB version? (Required)

master

[okJiang]

similar to #51488