fix foreign key assignment for unsharded record collections

Change-Id: Icbfe4e3fea8ef94cc634717c67af2c0da3462572
Reviewed-on: https://gerrit.instructure.com/30310
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>
fix reading polymorphic foreign keys when the type was not selected

Change-Id: Ibda3daffb2e656f878ccc1a6cdc5de8177173b8e
Reviewed-on: https://gerrit.instructure.com/30341
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: James Williams  <jamesw@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>