pgsql: Assert lack of hazardous buffer locks before possible catalog re

Assert lack of hazardous buffer locks before possible catalog read.

Commit 0bada39c83a150079567a6e97b1a25a198f30ea3 fixed a bug of this kind,
which existed in all branches for six days before detection.  While the
probability of reaching the trouble was low, the disruption was extreme.  No
new backends could start, and service restoration needed an immediate
shutdown.  Hence, add this to catch the next bug like it.

The new check in RelationIdGetRelation() suffices to make autovacuum detect
the bug in commit 243e9b40f1b2dd09d6e5bf91ebf6e822a2cd3704 that led to commit
0bada39.  This also checks in a number of similar places.  It replaces each
Assert(IsTransactionState()) that pertained to a conditional catalog read.

Back-patch to v14 - v17.  This a back-patch of commit
f4ece891fc2f3f96f0571720a1ae30db8030681b (from before v18 branched) to
all supported branches, to accompany the back-patch of commits 243e9b4
and 0bada39.  For catalog indexes, the bttextcmp() behavior that
motivated IsCatalogTextUniqueIndexOid() was v18-specific.  Hence, this
back-patch doesn't need that or its correction from commit
4a4ee0c2c1e53401924101945ac3d517c0a8a559.

Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/20250410191830.0e.nmisch@google.com
Discussion: https://postgr.es/m/10ec0bc3-5933-1189-6bb8-5dec4114558e@gmail.com
Backpatch-through: 14-17

Branch
------
REL_17_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/bcb784e7d2f9539ff65e63ffdb89631574034ec8

Modified Files
--------------
src/backend/storage/buffer/bufmgr.c | 67 +++++++++++++++++++++++++++++++++++++
src/backend/storage/lmgr/lwlock.c   | 15 +++++++++
src/backend/utils/adt/pg_locale.c   |  3 ++
src/backend/utils/cache/catcache.c  | 51 +++++++++++++++++++---------
src/backend/utils/cache/inval.c     | 14 ++++++--
src/backend/utils/cache/relcache.c  | 20 +++++++++--
src/backend/utils/mb/mbutils.c      |  3 +-
src/include/storage/bufmgr.h        |  3 ++
src/include/storage/lwlock.h        |  2 ++
src/include/utils/relcache.h        |  8 +++++
10 files changed, 166 insertions(+), 20 deletions(-)