Revert "[serve] Add basic REST API to dashboard"

[architkulkarni]

Reverts #2225

Seems to have broken linux://python/ray/workflow:tests/test_basic_workflows_2

Anecdotally, I started consistently getting this error with ray start --head roughly around the time of this PR being merged:

❯ ray start --head
Local node IP: 127.0.0.1
2022-02-15 18:29:31,278 ERROR services.py:1508 -- Failed to start the dashboard: Failed to start the dashboard, return code 1
 The last 10 lines of /tmp/ray/session_2022-02-15_18-29-29_064188_4744/logs/dashboard.log:
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/sessions.py", line 542, in request
    resp = self.send(prep, **send_kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/sessions.py", line 655, in send
    r = adapter.send(request, **kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=8265): Max retries exceeded with url: /api/jobs/submit (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fbae5e547f0>: Failed to establish a new connection: [Errno 61] Connection refused'))
2022-02-15 18:29:31,279 ERROR services.py:1509 -- Failed to start the dashboard, return code 1
 The last 10 lines of /tmp/ray/session_2022-02-15_18-29-29_064188_4744/logs/dashboard.log:
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/sessions.py", line 542, in request
    resp = self.send(prep, **send_kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/sessions.py", line 655, in send
    r = adapter.send(request, **kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=8265): Max retries exceeded with url: /api/jobs/submit (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fbae5e547f0>: Failed to establish a new connection: [Errno 61] Connection refused'))
Traceback (most recent call last):
  File "/Users/archit/ray/python/ray/_private/services.py", line 1485, in start_dashboard
    raise Exception(err_msg + last_log_str)
Exception: Failed to start the dashboard, return code 1
 The last 10 lines of /tmp/ray/session_2022-02-15_18-29-29_064188_4744/logs/dashboard.log:
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/sessions.py", line 542, in request
    resp = self.send(prep, **send_kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/sessions.py", line 655, in send
    r = adapter.send(request, **kwargs)
  File "/Users/archit/anaconda3/envs/ray-py38/lib/python3.8/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=8265): Max retries exceeded with url: /api/jobs/submit (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fbae5e547f0>: Failed to establish a new connection: [Errno 61] Connection refused'))

[edoakes]

Reverting w/o waiting for CI since pure revert