Need to handle constant filters (TRUE or FALSE) in planner

The expression handling framework (MB-25756, MB-26132) changed the way expressions are used in the planner. However, this framework currently does not properly handle constant filters (TRUE or FALSE) since such constant filters are not attached to any keyspace and thus not used during query planning process. Some queries with such constant filters do work ok with existing checks in the code but not all situations are handled properly.