message: change `net_usage_words` to `max_net_usage_words` in txn_test_gen_plugin
diff: @@ -122,7 +122,7 @@ struct txn_test_gen_plugin_impl {
  }
  trx.expiration = cc.head_block_time() + fc::seconds(30);
  - trx.net_usage_words = 500;
  + trx.max_net_usage_words = 500;
  trx.set_reference_block(cc.head_block_id());
  trx.sign(creator_priv_key, chainid);
  cc.push_transaction(packed_transaction(trx));
  @@ -184,7 +184,7 @@ struct txn_test_gen_plugin_impl {
  trx.expiration = cc.head_block_time() + fc::seconds(30);
  trx.set_reference_block(cc.head_block_id());
  - trx.net_usage_words = 5000;
  + trx.max_net_usage_words = 5000;
  trx.sign(txn_test_receiver_C_priv_key, chainid);
  cc.push_transaction(packed_transaction(trx));
  }
  @@ -257,7 +257,7 @@ struct txn_test_gen_plugin_impl {
  trx.context_free_actions.emplace_back(action({}, config::system_account_name, "nonce", fc::raw::pack(nonce++)));
  trx.set_reference_block(cc.head_block_id());
  trx.expiration = cc.head_block_time() + fc::seconds(30);
  - trx.net_usage_words = 100;
  + trx.max_net_usage_words = 100;
  trx.sign(a_priv_key, chainid);
  cc.push_transaction(packed_transaction(trx));
  }
  @@ -268,7 +268,7 @@ struct txn_test_gen_plugin_impl {
  trx.context_free_actions.emplace_back(action({}, config::system_account_name, "nonce", fc::raw::pack(nonce++)));
  trx.set_reference_block(cc.head_block_id());
  trx.expiration = cc.head_block_time() + fc::seconds(30);
  - trx.net_usage_words = 100;
  + trx.max_net_usage_words = 100;
  trx.sign(b_priv_key, chainid);
  cc.push_transaction(packed_transaction(trx));
  }
  