merge old and new gradebook envs
merge old and new gradebook envs

Old and New Gradebook ENVs no longer need to be separate, and are
causing friction with development. This consolidates them, alphabetizes
the properties, and removes a duplicate `sections` property. There is no
behavior change here. It is simply code cleanup.

closes TALLY-827
flag = none

test plan:
 * Smoke test gradebook

Change-Id: I0252b75d6968d643f03d43169a05f90c50465762
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/233383
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>
Reviewed-by: Gary Mei <4dff5ebcff9ed76793b70b9470ac64791a16ed11@instructure.com>
QA-Review: Robin Kuss <0b206b54367b2de0334896ea45826f0e3194bd35@instructure.com>
Product-Review: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>

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