fix backwards compatibility failure

We attempted to make this backwards compatible when removing the cache
queue support, but the old setting was "cache" not "queue"

Change-Id: I7f419365089a1d99dae5dec3e3f7cb18a92ae05f
Reviewed-on: https://gerrit.instructure.com/31030
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>
QA-Review: Brian Palmer <brianp@instructure.com>