message: feat(sdk-coin-sol): refactor
  Ticket:
diff: @@ -569,9 +569,6 @@ export class Sol extends BaseCoin {
  : 0;
  const scanLimit = !_.isUndefined(params.scan) && isInteger(params.scan) && params.scan >= 0 ? params.scan : 20;
  - let userSigningMaterial;
  - let backupSigningMaterial;
  -
  if (!params.bitgoKey) {
  throw new Error('missing bitgoKey');
  }
  @@ -581,7 +578,6 @@ export class Sol extends BaseCoin {
  }
  const bitgoKey = params.bitgoKey.replace(/\s/g, '');
  - const isUnsignedSweep = !params.userKey && !params.backupKey && !params.walletPassphrase;
  // Build the transaction
  const MPC = await EDDSAMethods.getInitializedMpcInstance();
  @@ -695,9 +691,7 @@ export class Sol extends BaseCoin {
  }
  const completedTransaction = await txBuilder.build();
  -
  const serializedTx = completedTransaction.toBroadcastFormat();
  -
  return {
  serializedTx: serializedTx,
  addressIndex: addressIndex,
  