[DocDB][xCluster][DDL] Replication halts even if schema matches but the schema was evolved with different steps on source and target

[Arjun-yb]

Jira Link: DB-6027

Description

Replication is halted even when schema matches on both source and target.

Version: 2.19.x

Create table at both sides

create table t1(id int primary key, name text);

setup replication and insert some rows and read at target ---- works

At source:

insert into t1(id, name) values(1,'Arjun');
insert into t1(id, name) values(2,'Sandeep');

At target:

select * from t1;
 id |  name
----+---------
  1 | Arjun
  2 | Sandeep

then alter table at source:

alter table t1 add column c1 text; ----- here type is text

and insert some rows

insert into t1(id, name, c1) values(3,'Hari','a');
insert into t1(id, name, c1) values(4,'Julien','b');
insert into t1(id, name, c1) values(5,'New','c');

here data is not replicated --- expected as there is mismatch in schema

then alter table at target

alter table t1 add column c1 int; ------ here type is int

data is not replicated ----- expected

alter at target

alter table t1 drop column c1
alter table t1 add column c1 text; ------ made it to text

here replication is not happened ------ expected as the alter id is different

then alter at source

alter table t1 drop column c1;
alter table t1 add column c1 text;
insert into t1(id, name, c1) values(6,'New','d');
demo1=# select * from t1;
 id |  name   | c1
----+---------+----
  5 | New     |
  1 | Arjun   |
  6 | New     | d
  4 | Julien  |
  2 | Sandeep |
  3 | Hari    |

after this replication should happen as both table has same schema
but it is not happening

demo1=# select * from t1;
 id |  name   | c1
----+---------+----
  1 | Arjun   |
  2 | Sandeep |

Expected: Replication should happen as schemas as compatible but they are not happening.

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[rajapriya371]

Observing this issue on 2.19.3.0-b140,2.18.5.0-b63