Revert "Transition to a new servicegroup schema"

This patch is causing some sort of huge performance hit.  Needs
investigation before production roll-out.

This reverts commit 46d5668a3e08ea9356db7a9e533a10bf2c0db7c2.

Change-Id: Ice42bf8d84eab09879f8a0d5c2ef67f223f18bff