pgsql: Ignore dropped columns during apply of update/delete.

Ignore dropped columns during apply of update/delete.

We fail to apply updates and deletes when the REPLICA IDENTITY FULL is
used for the table having dropped columns. We didn't use to ignore dropped
columns while doing tuple comparison among the tuples from the publisher
and subscriber during apply of updates and deletes.

Author: Onder Kalaci, Shi yu
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CACawEhVQC9WoofunvXg12aXtbqKnEgWxoRx3+v8q32AWYsdpGg@mail.gmail.com

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/3c12407f4cf735e17a8af54ab4306cd199601619

Modified Files
--------------
src/backend/executor/execReplication.c | 10 ++++--
src/test/subscription/t/100_bugs.pl    | 56 ++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 2 deletions(-)