Change the order of transaction verification steps in the validator nodes

[ibitec7]

Issue:
The transaction signature is being verified first and then the amount is being verified. This means that a computationally expensive task of verification is performed regardless of whether the rejection is of a simple issue.

Solutions:
Verify the less computationally expensive steps first such as the valid user and valid amount and then verify the signature, if the simple tests fail then reject the transaction before the computationally expensive test. This may increase the transaction throughput in cases of high fraudulent transactions like in the case of DDoS attacks.

Alternatives Considered:
N/A

Additional Context:
The latest test showed that more fraudulent transactions like in the case for DDoS attacks significantly slow down the time to finality of the transactions as the transaction throughput remains constant regardless. With this upgrade the transaction throughput would increase significantly and offset the performance degradation that causes a delayed time to finality.