clear default shard's primary shard cache on default shard reload
clear default shard's primary shard cache on default shard reload

Change-Id: I6f1fee4d70900903078432e830d20ffff5bd35e4
Reviewed-on: https://gerrit.instructure.com/92486
Reviewed-by: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
Product-Review: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
QA-Review: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
Tested-by: Jenkins

instructure/switchman,instructure/switchman