[Telemetry] Remove power metric from jsgamebench benchmark

Try removing metric to see if it has any affect on Mac 10.9 bot failures.

BUG=339162
TBR=tonyg@chromium.org

Review URL: https://codereview.chromium.org/182543006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253755 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253755