SOLR-4952: use solrconfig.snippet.randomindexconfig.xml in solrconfig.xml and crazy-path-to-config.xml; this included removing some unneccessary checks for indexConfig settings that already have their own explicit tests (merge r1510802)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1510817 13f79535-47bb-0310-9956-ffa450edef68