Revert of Re-land: Use script in depot_tools to retrieve builders from new cq.cfg

Revert of Re-land: Use script in depot_tools to retrieve builders from new cq.cfg (patchset #2 id:20001 of https://codereview.chromium.org/1148303006/)

Reason for revert:
Breaks the "git cl try" command, see chromium-dev@ and crbug.com/495219.

Traceback (most recent call last):
  File "/b/depot_tools/commit_queue.py", line 28, in <module>
    from cq_client import cq_pb2
  File "/b/depot_tools/third_party/cq_client/cq_pb2.py", line 9, in <module>
    from google.protobuf import symbol_database as _symbol_database
ImportError: cannot import name symbol_database

BUG=495219
Original issue's description:
> Re-land: Use script in depot_tools to retrieve builders from new cq.cfg
>
> TBR=akuegel@chromium.org, jochen@chromium.org
> TEST=ran git-cl-try on this CL on Win, Mac and Linux
>
> Committed: https://crrev.com/2c7fb79b2aad9d924dcbcd663e09f3022884f502
> Cr-Commit-Position: refs/heads/master@{#332369}

TBR=akuegel@chromium.org,jochen@chromium.org,sergiyb@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/cf0ee3bc5cb9f86398ca9c53a418e678b8ad952b
Cr-Commit-Position: refs/heads/master@{#332384}

[Peter Beverloo, 2015-06-02 14:36:34]

Created Revert of Re-land: Use script in depot_tools to retrieve builders from
new cq.cfg

[commit-bot: I haz the power, 2015-06-02 14:36:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160783004/1

[commit-bot: I haz the power, 2015-06-02 14:38:12]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-02 14:39:11]

Patchset 1 (id:??) landed as
https://crrev.com/cf0ee3bc5cb9f86398ca9c53a418e678b8ad952b
Cr-Commit-Position: refs/heads/master@{#332384}

[Sergiy Byelozyorov, 2016-03-23 15:15:49]

lgtm

[Sergiy Byelozyorov, 2016-03-23 15:18:18]

lgtm