return integers from find_ids_in_ranges for integers

refs CNVS-7032

Change-Id: I238aad57923ca0c841843bd8a90f3789082d449f
Reviewed-on: https://gerrit.instructure.com/28554
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Anthus Williams <awilliams@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>