wait for replication when clearing account downstream caches
wait for replication when clearing account downstream caches

refs FOO-2079

the queries that these caches protect are pretty critical, and often
run against the secondary, so make sure the secondary is up to date

Change-Id: Ia2e6ce9c45911eebf04630d1e4464d128980c1b8
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/269229
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: August Thornton <9adc7a1161ddf32ff608de792a7e50179545f026@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms