enforce not null constraint on shardgroupid for shards

src/backend/distributed/sql/citus--11.2-1--11.3-1.sql

@@ -46,4 +46,9 @@ WHERE shard.logicalrelid = shardgroup.logicalrelid
        shard.shardmaxvalue = shardgroup.shardmaxvalue
        OR (    shard.shardmaxvalue      IS NULL
            AND shardgroup.shardmaxvalue IS NULL)
-  );
+  );
+
+-- risky, but we want to fail quickly here. If there are cases where a shard is not associated correctly with a
+-- shardgroup we would not want the setup to use the new Citus version as it hard relies on the shardgroups being
+-- correctly associated.
+ALTER TABLE pg_catalog.pg_dist_shard ALTER COLUMN shardgroupid SET NOT NULL;