DERBY-6064: Failures in upgradeTests.Changes10_9 related to index cardinality statistics

Merged fix from trunk (revisions 1441923 and 1442483).


git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/branches/10.9@1442552 13f79535-47bb-0310-9956-ffa450edef68