Improve Trie log branch pruning

[non-fungible-nelson]

There are several ways to optimize pruning. The flat database has perfect pruning but on the branch side we can still improve things. Bonsai, thanks to the fact that it saves nodes by location, allows you to replace old nodes with new ones automatically and therefore have efficient pruning. But when we don't replace an old location we leave it present. This should perhaps be tracked and deleted in the background afterwards

We can also be sure that we are cleaning everytime the storage when a storage become empty (selfdestruct is ok but we need to check if there are other egdecases)