Idea: batch trie key generation inside a background thread

[thomas-quadratic]

Description

Currently, trie keys generation will gather all transactions data and generate a single large batch of trie keys at once.
However, there are already mechanisms implemented in Besu to preload those trie keys in a background thread during block processing.
We should investigate using that mechanism.

[matkt]

maybe not really important. for the moment seems to be good with the current implementation but we will have to test with bigger blocks

[matkt]

link to the PR hyperledger/besu#7206