OAK-1462 - Aggregate Index isn't usable in an osgi environment

Disabling the OSGi registration for now as it might cause issue when an aggregate index wrapper is also registered. As both of them would be invoked for Observer while we only require one.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1588154 13f79535-47bb-0310-9956-ffa450edef68