Add timestamp in the validation node election

[Neylix]

Is your feature request related to a problem?

Currently the validation node election is based on transaction data and the daily nonce seed. Therefore if a transaction fail to be validated and the exact same transaction is sent again the validation nodes will be the same until the daily nonce seed change.
But is one of the validation nodes (mainly the coordinator) has a wrong state or cannot retrieve some data, the stamp will be wrong and the transaction cannot be validated for the entire day.

Describe the solution you'd like

To avoid this issue, we can add a timestamp in the election so the elected nodes will be always different.
The timestamp used could be the one used by the welcome node which is sent in the StartMining message (the ref timestamp)

Additional context

No response

Epic

No response