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.
We require `PESSIMISTIC`, and in fact I had to change quite a few configurations that used `OPTIMISTIC`. Honestly, I don't see how the ModeShape logic could work with `OPTIMISTIC `, or am I misting something?

And we do (or should) preemptively lock everywhere now. I've thought about putting back the lock request in the `SchematicEntry.edit()` method to always ensure this, but I wasn't sure it was worth the overhead and that instead it'd be better to review the code to make sure that lock is always called. Alternatively, we could add an `edit(boolean acquireLock)` method that we could use when we know that we've acquired a lock (in `WritableSessionCache`), and then have `edit(...)` delegate to `edit(false)`. Then we'd know we are always locking for sure, but in `WritableSessionCache` (or other places we know we're locking) we could skip the extra lock. Thoughts?