message: refactor(core): deprecate hdPath in xtz.ts
  The previous method ignored the leading `/`, so don't add it to begin
  with.
  Since we can see how the path is constructed we don't have to use
  `sanitizeLegacyPath()` here.
  Issue:
diff: @@ -25,7 +25,6 @@ import { BitGo } from '../../bitgo';
  import { NodeCallback } from '../types';
  import BigNumber from 'bignumber.js';
  import { MethodNotImplementedError } from '../../errors';
  -import { hdPath } from '../../bitcoin';
  import * as bitcoin from '@bitgo/utxo-lib';
  export interface XtzSignTransactionOptions extends SignTransactionOptions {
  @@ -170,7 +169,7 @@ export class Xtz extends BaseCoin {
  */
  deriveKeyWithPath({ key, path }: { key: string; path: string }): string {
  const keychain = bitcoin.HDNode.fromBase58(key);
  - const derivedKeyNode = hdPath(keychain).derive(path);
  + const derivedKeyNode = keychain.derivePath(path);
  return derivedKeyNode.toBase58();
  }
  @@ -203,7 +202,7 @@ export class Xtz extends BaseCoin {
  if (chain === 0 && index === 0) {
  key = params.prv;
  } else {
  - const derivationPath = `/0/0/${chain}/${index}`;
  + const derivationPath = `0/0/${chain}/${index}`;
  key = self.deriveKeyWithPath({ key: params.prv, path: derivationPath });
  }
  txBuilder.sign({ key });
  