Split manage groups spec in two

Fixes CNVS-16485

Test Plan:
Ensure tests still pass

Change-Id: I2b2e26534eeafca3400f245a582cda808f2181f2
Reviewed-on: https://gerrit.instructure.com/43354
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Mark Severson <markse@instructure.com>
Product-Review: Matthew Wheeler <mwheeler@instructure.com>
QA-Review: Matthew Wheeler <mwheeler@instructure.com>