pgsql: Fix NLS for incorrect GUC enum value hint message

Fix NLS for incorrect GUC enum value hint message

The translation markers were applied at the wrong place, so no string
was extracted for translation.

Also add translator comments here and in a similar place.

Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Discussion: https://www.postgresql.org/message-id/2c961fa1-14f6-44a2-985c-e30b95654e8d%40eisentraut.org

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/0fc33b00536cf395b44260b6fc76b6b1d6fc0bcb

Modified Files
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src/backend/replication/logical/relation.c | 1 +
src/backend/utils/misc/guc.c               | 9 ++++++---
2 files changed, 7 insertions(+), 3 deletions(-)