message: [test] fix mock txn gas.
diff: @@ -68,7 +68,7 @@ impl MockTxnGenerator {
  .sequence_number();
  // add some randomness too.
  let mut rng = rand::thread_rng();
  - let amount_to_transfer = rng.gen_range(5000u64, 10000u64);
  + let amount_to_transfer = rng.gen_range(500000000u64, 1000000000u64);
  // transfer will create account if it not exists.
  let txn = <E as TransactionExecutor>::build_mint_txn(
  @@ -104,7 +104,7 @@ impl MockTxnGenerator {
  a_seq_number: u64| {
  // add some randomness.
  let mut rng = rand::thread_rng();
  - let amount_to_transfer = rng.gen_range(10000000u64, 50000000u64);
  + let amount_to_transfer = rng.gen_range(1000u64, 5000u64);
  let transfer_txn = <E as TransactionExecutor>::build_transfer_txn(
  a.0,
  AuthenticationKey::from_public_key(&a.1.public_key).to_vec(),
  