Add test with multirange type for pg_restore_attribute_stats()

Add test with multirange type for pg_restore_attribute_stats()

This commit adds a test for pg_restore_attribute_stats() with the
injection of statistics related to a multirange type.  This case is
supported in statatt_get_type() since its introduction in ce207d2a7901,
but there was no test in the main regression test suite to check for the
case where attribute stats is restored for a multirange type, as done by
multirange_typanalyze().

Author: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://postgr.es/m/CADkLM=c3JivzHNXLt-X_JicYknRYwLTiOCHOPiKagm2_vdrFUg@mail.gmail.com