DERBY-6045 (in list multi-probe by primary key not chosen on tables with >256 rows)

Added a new test scenario where we add about 10K rows into a table with primary key and check if we are still using index scan for the queries being tested

Additionally, cleaned up the test a little bit.



git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1446048 13f79535-47bb-0310-9956-ffa450edef68