res.clearCookie() now ignores maxAge

[tjarbo]

This pr fixes #4851.

I have ...

• [X] added a new test that covers my changes
• [X] run linter

[Segmentational]

Testing the changes, in the unit-test:

  // ... blah blah blah
  [Symbol(kOutHeaders)]: [Object: null prototype] {
    'x-powered-by': [ 'X-Powered-By', 'Express' ],
    'set-cookie': [
      'Set-Cookie',
      'sid=; Path=/admin; Expires=Thu, 01 Jan 1970 00:00:00 GMT'
    ]
  }
}

confirms the maxAge attribute is indeed removed. Output following the request.end() call yields

// ... blah blah blah
 _maxListeners: undefined,
  _enableHttp2: false,
  _agent: false,
  _formData: null,
  method: 'GET',
  url: 'http://127.0.0.1:46159/',
  _header: {},
  header: {},
  writable: true,
  _redirects: 0,
  _maxRedirects: 0,
  cookies: '',
// ... blah blah blah

Great, cookies are not set in the raw http response!

Due to my little experience in our test suite, another PR would be useful. But to my understanding things are looking good.