client: persist correct allocation state

[mismithhisler]

Description

Currently the allocRunner's allocation is never updated with the correct state. All state updates made to servers are done by sending a "stripped" version of an allocation with the correct state.

Since the allocation object doesn't appear designed to be mutated, we can copy it and update that copy with the correctly derived state and store it when calling PersistState()

Testing & Reproduction steps

Links

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[Juanadelacuesta]

It looks pretty good, but do you mind adding some testing? Or maybe expand on this one. Also remember the backport labels