Remove dbus-launch workaround now that it's been propagated to runtest.py.

BUG=309093
TBR=dtu@chromium.org

Review URL: https://codereview.chromium.org/46183003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231172 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231172