pgsql: Fix new pg_publication_tables query.

Fix new pg_publication_tables query.

The addition of published column names forgot to filter on attisdropped,
leading to cases where you could see "........pg.dropped.1........"
or the like as a reportedly-published column.

While we're here, rewrite the new subquery to get a more efficient plan
for it.

Hou Zhijie, per report from Jaime Casanova. Back-patch to v15 where
the bug was introduced. (Sadly, this means we need a post-beta4
catversion bump before beta4 has even hit the streets. I see no
good alternative though.)

Discussion: /messages/by-id/Yxa1SU4nH2HfN3/i@ahch-to

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/20b6847176976da9cae6103475b967e6c2971898

Modified Files
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src/backend/catalog/system_views.sql | 9 ++++-----
src/include/catalog/catversion.h | 2 +-
src/test/regress/expected/rules.out | 9 ++-------
3 files changed, 7 insertions(+), 13 deletions(-)