Refresh test schema to match current platform schema

The hand written test schema had drifted from the actual platform schema. Columns which are present now match
their real definitions in name, type and nullability:

 * auth_user is now users_user
 * msgs_msg.quick_replies is now quickreplies jsonb
 * add flows_flowstartcount which we delete from when deleting orphaned starts
 * fix nullability of flows_flowrun.session_uuid, flows_flowrun.results and msgs_msg.next_attempt
 * use uuid type for uuid columns which are no longer varchar
 * use bigint/bigserial for ids which are no longer integer
 * fix varchar lengths on name and attachment columns
 * add missing non-null columns and foreign keys
 * remove drops for tables which are never created

Author: rowanseymour