Adding timer instrumentation for BatchSplitter and RollupTypeCacher

https://jira.rax.io/browse/CMD-355

* Added instrumentation for BatchSplitter and RollupTypeCacher ingestion processors
* Check if any other processors need that instrumentation 
* Check if any tests need to be added
Same points here as I made in BatchSplitter.java.

nit: could you stick to the established styles? keep opening curly brackets on the same line as the rest of the method signature.