Refactor vaults to be fully virtualized

[turadg]

What is the Problem Being Solved?

#4345 is to use virtual objects in vaults, which can be achieved without meeting the full MN-1 scaling requirement that high cardinality state be virtualized.

To be fully virtualized requires #4513 but partial virtualization need not be blocked.

Description of the Design

X is fully virtualized if all state that is 1:1 with X is virtualized as well.

In particular, notifiers which can't be virtualized until #4513

Security Considerations

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Test Plan

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