pend specs_require_sharding in rails 3

closes #CNVS-13847

Change-Id: I10ec77968a4462eece3e199ad2bd0ae5d506899f
Reviewed-on: https://gerrit.instructure.com/37441
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>