Use addDocument instead of updateDocument while reindexing with Lucene

Currently the DefaultIndexWriter uses updateDocument while adding/updating document in index. This is fine for incremental indexing where we cannot be sure if index already has that entry. This call first does a search for existing document matching the term and then deletes and add the new document

However for reindex case where we start from empty index we can use addDocument. This avoids the extra work for search

In test where index had ~70M entries switch to addDocument resulted in 10 min reduction in reindexing timings