Work on ITest-2 Failures:
- More work around 1071330 which added caching and last-update
  logic around SystemSettings.  Adding an internal-only local SLSB
  method which allows write of readOnly system settings.  This is
  analogous to the one I added a few minutes ago for a single setting.
- Convert SynchronizationManagerbeanTest to use SystemSettings as opposed
  to the deprecated systemConfig API, and use the internal SLSB methods
  as needed.