message: refactor(core): remove deprecated signMessage tests
  This is already covered by `bip32util.ts` tests
  Issue:
diff: @@ -9,7 +9,6 @@ import { getBuilder, BaseCoin, Eth } from '@bitgo/account-lib';
  import * as ethAbi from 'ethereumjs-abi';
  import * as ethUtil from 'ethereumjs-util';
  import * as bitgoUtxoLib from '@bitgo/utxo-lib';
  -import * as bitcoinMessage from 'bitcoinjs-message';
  import { coins, ContractAddressDefinedToken } from '@bitgo/statics';
  describe('ETH-like coins', () => {
  @@ -213,27 +212,6 @@ describe('ETH-like coins', () => {
  });
  });
  - describe('Sign message:', () => {
  - it('should sign and validate a string message', async function () {
  - const keyPair = basecoin.generateKeyPair();
  - const message = 'hello world';
  - const signature = await basecoin.signMessage(keyPair, message);
  - const hdNode = bitgoUtxoLib.HDNode.fromBase58(keyPair.pub);
  -
  - bitcoinMessage.verify(message, hdNode.keyPair.getAddress(), signature).should.equal(true);
  - });
  -
  - it('should fail to validate a string message with wrong public key', async function () {
  - const keyPair = basecoin.generateKeyPair();
  - const message = 'hello world';
  - const signature = await basecoin.signMessage(keyPair, message);
  -
  - const otherKeyPair = basecoin.generateKeyPair();
  - const hdNode = bitgoUtxoLib.HDNode.fromBase58(otherKeyPair.pub);
  - bitcoinMessage.verify(message, hdNode.keyPair.getAddress(), signature).should.equal(false);
  - });
  - });
  -
  describe('Sign transaction:', () => {
  const xprv =
  'xprv9s21ZrQH143K3D8TXfvAJgHVfTEeQNW5Ys9wZtnUZkqPzFzSjbEJrWC1vZ4GnXCvR7rQL2UFX3RSuYeU9MrERm1XBvACow7c36vnz5iYyj2';
  