Update cq.cfg to use new name for committers group.

infra/config/cq.cfg

 # See http://luci-config.appspot.com/schemas/projects/refs:cq.cfg for the
 # documentation of this file format.
 
 version: 1
 cq_name: "chromium"
 cq_status_url: "https://chromium-cq-status.appspot.com"
 commit_burst_delay: 60
 max_commit_burst: 2
 
 rietveld {
   url: "https://codereview.chromium.org"
 }
 
 verifiers {
   reviewer_lgtm {
-    committer_list: "external/project-chromium-committers"
+    committer_list: "project-chromium-committers"

[Vadim Sh., 2017/02/03 00:40:21]

https://chrome-infra-auth.appspot.com/auth/groups#project-chromium-committers

     dry_run_access_list: "project-chromium-tryjob-access"
   }
 
   tree_status {
     tree_status_url: "https://chromium-status.appspot.com"
   }
 
 # NOTE: when adding new configs to the commit queue, please contact
 # chrome-eng-review per
 # https://sites.google.com/a/chromium.org/dev/developers/testing/chromium-build-infrastructure/tour-of-the-chromium-buildbot?pli=1#TOC-Adding-new-build-configurations-and-tests-to-the-main-Chromium-waterfall-Commit-Queue
@@ skipping 56 matching lines @@
       builders { name: "win_clang" }
     }
   }
 
 # NOTE: when adding new configs to the commit queue, please contact
 # chrome-eng-review per
 # https://sites.google.com/a/chromium.org/dev/developers/testing/chromium-build-infrastructure/tour-of-the-chromium-buildbot?pli=1#TOC-Adding-new-build-configurations-and-tests-to-the-main-Chromium-waterfall-Commit-Queue
 
   sign_cla {}
 }