Fix to various naming related issues in _rif40_common_partition_create()
Changed to _rif40_hash_bucket_check() check function

Hash partition elimination (via the CHECK constraint) currently does not
work as Postgres only supports range values (e.g. year = 1999; not
study_id = rif40_sql_pkg._rif40_hash_bucket_check(study_id, 16 /* total
buckets */, 15 /* bucket requested */)

Need a simpler example and look at the Postgres source code in
predtest.c