Improve release frequency for signing keys #841
Description
Currently, the number of singing keys gets depleted quite fast, due to the frequent invalid transactions (nonce too low/nonce too high) sent by trading bots etc.
Because the trading bots send transactions very frequently, they have higher chances of acquiring the signing keys that get released. This causes bad UX for real users, that often have their transactions dropped, due to lack of signing keys.
The release frequency of the keys used for these invalid transaction, is quite high now: https://github.com/onflow/flow-evm-gateway/blob/main/services/requester/keystore/key_store.go#L72-L83 . It's 600 blocks, or about 10 minutes.
We can improve that by checking for the result status of the Flow transaction that used a certain signing key.