pgsql: amcheck: Reduce debug message verbosity.

amcheck: Reduce debug message verbosity.

Empty sibling pages can occasionally be much more common than any other
event that we report on at elevel DEBUG1. Increase the elevel for
relevant cases to DEBUG2 to avoid overwhelming the user with relatively
insignificant details.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/65445469d6de3670f3e027236613e093e119ec55

Modified Files
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contrib/amcheck/verify_nbtree.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)