OAK-1966 - Add Hint for selecting more performant index in MongoDocumentStore#query

Disabling the modified index based approach for now (setting default to -1) untill this is fully tested

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1611021 13f79535-47bb-0310-9956-ffa450edef68
OAK-1972: Async property index update may fail on DocumentMK with more than 100 index changes

Test to reproduce the issue

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1611041 13f79535-47bb-0310-9956-ffa450edef68