Test binary tree post flip cache invalidation

## Observation

Many clients will store caching layers on top of the database for state. Some of these caches will flush at certain intervals like after 128 blocks.

## Suggestion

This is an issue to track testing these caching mechanisms. One thing in particular is that rpc methods should not use the MPT cache post flip.

I would recommend triggering cache invalidations etc, though this requires knowing the caching mechanism for each client to do effectively

Start by identifying the RPC methods and client MPT cache behavior relevant after the post flip. Define scenarios that trigger cache invalidation, including interval-based flushing such as after 128 blocks, then verify that RPC methods do not use the MPT cache post flip across the relevant clients.

Written by the indexing model from the issue text.