Uncouple scheduler stats from volume creation

Capture and report scheduler stats independently from volume creation.
Without this scheduler stats were not reported until the first volume
creation and were subsequently only updated each time a volume was
created.

Change-Id: Ia1a809ba10e0595e6c255fde683f7c252377ac09
Fixes-bug: 1402790
Fixes-bug: 1402806
Merge "Uncouple scheduler stats from volume creation"