MB-14716 indexer: Cleanup bucket connections
MB-14716 indexer: Cleanup bucket connections

Whenever a bucket becomes unused in indexer timekeeper, its
connections can be cleaned up.

Change-Id: Ie3bf6ec358c0b2c1f6f7d225a86beffbd5df3f90

jchris/indexing,jchris/indexing,jchris/indexing,jchris/indexing