SOLR-6597: Removed SolrIndexConfig parameter from one of the SolrIndexSearcher constructor, where it was never really used

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1629772 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5992: add SI tests; remove FieldInfos from SegmentInfosWrite.write

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1629774 13f79535-47bb-0310-9956-ffa450edef68