GetRelationPublicationActions. - Remove unreachable code

Hi hackers.

There appears to be some unreachable code in the relcache function
GetRelationPublicationActions.

When the 'relation->rd_pubactions' is not NULL then the function
unconditionally returns early (near the top).

Therefore, the following code (near the bottom) seems to have no
purpose because IIUC the 'rd_pubactions' can never be not NULL here.

if (relation->rd_pubactions)
{
pfree(relation->rd_pubactions);
relation->rd_pubactions = NULL;
}

The latest Code Coverage report [1] also shows that this code is never executed.

5601 3556 : if (relation->rd_pubactions)
5602 : {
5603 0 : pfree(relation->rd_pubactions);
5604 0 : relation->rd_pubactions = NULL;
5605 : }

~~

PSA a patch to remove this unreachable code.

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[1] https://coverage.postgresql.org/src/backend/utils/cache/relcache.c.gcov.html

Kind Regards,
Peter Smith.
Fujitsu Australia