[BUG] be may be core dump if the server upgrade from 0.11

[yangzhg]

Describe the bug
If the server upgrade from 0.11 and has a duplicate table. After upgrade we add a column by linked schema change, this will be cause a core dump

To Reproduce
Steps to reproduce the behavior:

1. in version 0.11 create a duplicate table, and load some data;

CREATE TABLE table1
(
    siteid INT DEFAULT '10',
    citycode SMALLINT,
    username VARCHAR(32) DEFAULT '',
    pv BIGINT DEFAULT '0'
)
duplicate KEY(siteid, citycode, username)
DISTRIBUTED BY HASH(siteid) BUCKETS 10
PROPERTIES("replication_num" = "1");
insert into table1 values
(1,1,"jim",2),
(2,1,"grace",2),
(3,2,"tom",2),
(4,3,"bush",3),
(5,3,"helen",3);

2. upgrade to 0.12
3. add a column by linked schema change, like ALTER TABLE table1 ADD COLUMN tc_type varchar(24) DEFAULT "all" AFTER pv;
4. See error

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