pgsql: Clean up sloppy coding in publicationcmds.c's OpenTableList().

Clean up sloppy coding in publicationcmds.c's OpenTableList().

Remove dead code (which would be incorrect if it weren't dead),
per report from Pan Bian. Add a CHECK_FOR_INTERRUPTS in the
inner loop over child relations, because there's little point
in having one in the outer loop if there's not one here too.
Minor stylistic adjustments and comment improvements.

Seems to be aboriginal to this code (cf commit 665d1fad9).
Back-patch to v10 where that came in, not because any of this
is significant, but just to keep the branches looking similar.

Discussion: https://postgr.es/m/15539-06d00ef6b1e2e1bb@postgresql.org

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/aaf7b3bd6f715078867092e7e95c94a1e4222646

Modified Files
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src/backend/commands/publicationcmds.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)