Undrain CQ.

But leave doc for troopers in case this is needed again in the future.

R=jchinlee@chromium.org

Bug: 817498
Change-Id: I46c33c17752f52394bb96cbd3d7bbbe944f89a17
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/942240
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Jao-ke Chin-Lee <jchinlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539948}

infra/config/branch/cq.cfg

@@ -8,8 +8,10 @@ git_repo_url: "https://chromium.googlesource.com/chromium/src"
 commit_burst_delay: 60
 max_commit_burst: 2
 
-# TODO(tAandrii): remove this after outage of crbug/817498 is over.
-draining_start_time: "2018-02-28T20:00:00Z"  # 12PM PST(MTV) time.
+# Trooper, if you want to drain CQ such that CQ stops triggering new trybots,
+# uncomment line below. The timestamp cutoff time in UTC s.t. all CLs
+# on which CQ was triggered **after** this time are ignored by CQ.
+# draining_start_time: "2018-02-28T20:00:00Z"
 
 gerrit {}