pgsql: Don't choose an invalid index for REPLICA IDENTITY FULL lookups.

Don't choose an invalid index for REPLICA IDENTITY FULL lookups.

For a REPLICA IDENTITY FULL remote relation whose local counterpart has
no primary key or replica identity, FindUsableIndexForReplicaIdentityFull()
chooses the first index of a suitable shape from RelationGetIndexList().
That list excludes only indexes that are not indislive, so an invalid
index left behind by a failed CREATE INDEX CONCURRENTLY can be selected.

Such an index need not contain every row. Consequently, changes for rows
that it fails to find can be silently dropped as missing-tuple conflicts.
If the index contains no rows at all, the scan can instead error out and
cause the apply worker to exit.

Skip invalid indexes, as the planner does.

Author: Mikhail Nikalayeu <mihailnikalayeu(at)gmail(dot)com>
Reviewed-by: Miłosz Bieniek <bieniek(dot)milosz(at)proton(dot)me>
Reviewed-by: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Reviewed-by: Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com>
Reviewed-by: Vignesh C <vignesh21(at)gmail(dot)com>
Reviewed-by: Ajin Cherian <itsajin(at)gmail(dot)com>
Discussion: https://postgr.es/m/CADzfLwWuubcbJBDRZ_J1SSqHDNjNmUYSAgf5y=17LxmP401xbw@mail.gmail.com
Backpatch-through: 16, where it was introduced

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ea9c9432c828c6ba9e38bdd0bccd3f63507594fc

Modified Files
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src/backend/replication/logical/relation.c | 16 +++++-
src/test/subscription/t/032_subscribe_use_index.pl | 59 ++++++++++++++++++++++
2 files changed, 74 insertions(+), 1 deletion(-)