test that restarting v43-wallet will re-subscribe to v14-bank asset subscriptions

[warner]

As part of #8499 (look for v14-bank-v28-provisionpool, the second section), we investigate how v43-wallet will react when it is upgraded, specifically with respect to the promises that it follows from v14-bank. These promises appear in v43-wallet in makeAssetRegistry() when it calls E(poolBank).getAssetSubscription(). This code uses observeIteration (which tolerates the decider getting upgraded/restarted), however it doesn't use a DurablePromiseWatcher, so our concern is what happens when the subscriber (v43-wallet) is upgraded/restarted.

This code is called from a prepare method, which provides evidence thaht it will be called each time v43-wallet is restarted. If so, we're good. If not, the new version of the vat might not correctly follow new assets created after upgrade.

We've already restarted v43-wallet once, in gov-49 (which activated 21-Sep-2023). I don't know if we've added any assets since then.

The task for this ticket is to test this case, ideally through a3p or some reproducible mechanism, and demonstrate that:

• 1: the new version of v43-wallet calls getAssetSubscription()
• 2: the upgraded wallet vat correctly reacts to new assets being announced by v14-bank

[dckc]

restarting v43-wallet has happened on mainnet, in proposal 49.
https://github.com/Agoric/agoric-3-proposals/tree/main/proposals/49%3Asmart-wallet-nft

and it evidently did subscribe to new vbank assets, cuz stATOM was added later in proposal 55
https://github.com/Agoric/agoric-3-proposals/tree/main/proposals/55%3Astatom-vaults

So we have an a3p test of this already.

It's reasonably straightforward to see how this happened:

• restarting the contract invokes the start function (called prepare in this case)
• prepare calls makeAssetRegistry
• makeAssetRegistry calls E(assetPublisher).getAssetSubscription()

[dckc]

@Chris-Hibbert concurs that we've addressed this