remove unneeded path to react in requirejs config

there is a file in public/javascripts/react.js
that takes care of this for us

Change-Id: Iad46ebf58265f415a47694b36a930f61cb2641d8
Reviewed-on: https://gerrit.instructure.com/38087
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Sterling Cobb <sterling@instructure.com>
Product-Review: Ryan Shaw <ryan@instructure.com>
QA-Review: Ryan Shaw <ryan@instructure.com>