Regenerate the latest_build_status table

As it doesn't handle wierdness for statuses, like builds being canceled with a
timestamp of 0.

sqitch/revert/regenerate_latest_build_status.sql

@@ -0,0 +1,7 @@
+-- Revert guix-data-service:regenerate_latest_build_status from pg
+
+BEGIN;
+
+-- XXX Add DDLs here.
+
+COMMIT;