DS-2111 Remove lucene index operation at end of media filter run

https://jira.duraspace.org/browse/DS-2111

Lucene index is deprecated nowadays, so we don't need to maintain it. Running the media filter has had a call to reindex the lucene index after all of these bitstreams get generated. According to Terry/Tim, Discovery is going to automagically index changed files, so we don't need to trigger a manual index. So, this PR removes the reindexing at the end of media filter.