reset schema cache after migrating for new shards
reset schema cache after migrating for new shards

Change-Id: I218bbd62f86ccc5f8ef3835e5abf097b639899e3
Reviewed-on: https://gerrit.instructure.com/28213
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
Product-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>

instructure/switchman,ccutrer/switchman,instructure/switchman,krrg/switchman