[BUG]Invalidate relcache when setting REPLICA IDENTITY

Hi

I think I found a bug related to logical replication(REPLICA IDENTITY in specific).
If I change REPLICA IDENTITY after creating publication,  the DELETE/UPDATE operations won't be replicated as expected. 

For example:
-- publisher
CREATE TABLE tbl(a int, b int);
ALTER TABLE tbl ALTER COLUMN a SET NOT NULL;
CREATE UNIQUE INDEX idx_a ON tbl(a);
ALTER TABLE tbl ALTER COLUMN b SET NOT NULL;
CREATE UNIQUE INDEX idx_b ON tbl(b);
ALTER TABLE tbl REPLICA IDENTITY USING INDEX idx_a;
CREATE PUBLICATION pub FOR TABLE tbl;
ALTER TABLE tbl REPLICA IDENTITY USING INDEX idx_b;
INSERT INTO tbl VALUES (1,1);

-- subscriber
CREATE TABLE tbl(a int, b int);
ALTER TABLE tbl ALTER COLUMN b SET NOT NULL;
CREATE UNIQUE INDEX idx_b ON tbl(b);
ALTER TABLE tbl REPLICA IDENTITY USING INDEX idx_b;
CREATE SUBSCRIPTION sub CONNECTION 'dbname=postgres port=5432' PUBLICATION pub;
SELECT * FROM tbl;

-- publisher
postgres=# UPDATE tbl SET a=-a;
UPDATE 1
postgres=# SELECT * FROM tbl;
a  | b
----+---
 -1 | 1 
(1 row)

-- subscriber
postgres=# SELECT * FROM tbl;
 a | b
---+---
 1 | 1
(1 row)

(a in subscriber should be -1)

But if I restart a psql client before executing UPDATE operation in publication, it works well. 
So I think the problem is: when using "ALTER TABLE ... REPLICA IDENTITY USING INDEX ...", relcahe was not invalidated.

Attach a patch to fix it, I also added a test case for it.(Hou helped me to write/review this patch, which is very kind of him)

FYI: I also tested that same problem could be reproduced on PG10 ~ PG14. (Logical replication is introduced in PG10.)
So I think backpatch is needed here.

Regards
Tang