Use the new tools/clean_output_directory.py script for clobbering builders.
Use the new tools/clean_output_directory.py script for clobbering builders.

This will unify our clobbering functionality across builders that use annotated steps and builders with test setup in the buildbot source.
TBR=foo

Review URL: https://chromiumcodereview.appspot.com/10834305

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@151464 0039d316-1c4b-4281-b951-d872f2087c98

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