AggregateRemoveRule fails to remove the top Aggregate for below SQL
The reason is that RelMdColumnUniqueness doesn't take the filtering condition into consideration when checking uniqueness of columns.
This PR proposes to refine RelMdColumnUniqueness for Filter, thus to strengthen AggregateRemoveRule.
Resolving this Jira will help a lot for
CALCITE-3334 by removing the redundant compensation Aggregate when doing materialization matching