Don't get IndexState, ShardState and IdFieldDef individually for each AddDocumentRequest in AddDocumentHandler.runIndexingJob

[sarthakn7]

The addDocuments endpoint in LuceneServer.java already calls AddDocumentHandler.runIndexingJob with documents per index. We can add the indexName as a parameter to runIndexingJob and make the code clearer by not getting IndexState for each AddDocumentRequest individually.