don't replace priceAggregator, scaledPriceAuthority contract installations (WIP)

[dckc]

goal: fixes: https://github.com/0xpatrickdev/agoric-vault-collateral-proposal/issues/7

draft pending...

• [x] prune permits
• [x] prune contract bundles
• [x] update contract references

[dckc]

er... I neglected to integrate the fixup. Is it worth another release for that, @turadg?