Stop sending stepFinished updates from the tryserver.
Stop sending stepFinished updates from the tryserver.

This is not needed after https://codereview.appspot.com/49430044/

In fact, Rietveld logs contain lots of
"Stop sending events of type stepFinished" lines.

BUG=317931

Review URL: https://codereview.chromium.org/137833007

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@247808 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build