make this test value configurable via cli

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1443792 13f79535-47bb-0310-9956-ffa450edef68
better logging when cleaning temp group index

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1443793 13f79535-47bb-0310-9956-ffa450edef68