RE: Fix apply worker crash when subscriber table has only a deferrable primary key

Dear Nisha,

> My understanding is also the same. Thanks for the patch; I’ve verified the fix.
>
> Here is the updated version, merged with v3-0001.
>
> v4-0001: Updated stale comments in RelationFindDeletedTupleInfoSeq(),
> corrected the new comments in FindDeletedTupleInLocalRel(), and added
> an assertion that the whole row is compared only when the publisher
> uses REPLICA IDENTITY FULL.

Thanks. One comments for 0001:

```
/* Without such an index, every column is compared. */
Assert(relmapentry->idxisreplident ||
relmapentry->remoterel.replident == REPLICA_IDENTITY_FULL);
```

I feel the first condition is something like transitive. Here we want to confirm
whether 1) we can pick indexed columns or 2) all columns are replicated. So it's
better to directly check the existence of the index:

```
Assert(OidIsValid(idxoid) ||
relmapentry->remoterel.replident == REPLICA_IDENTITY_FULL);
```

Best regards,
Hayato Kuroda
FUJITSU LIMITED