MODE-2323 Removed the proxy layer and delta write functionality in Schematic

ModeShape's is no longer using Infinispan in ways where these pieces of functionality are useful.
Removing them should simplify the logic to represent more of what we're actually doing. See MODE-2323 for details.
On second thought, theoretically a single writer use case is a possibility, but is it a practical or likely possibility? And do we need to optimize for that case, especially since we're not sure what `FAIL_SILENTLY` _really_ does?