ignore quals for null relid

[Nowheresly]

It seems the client-side is not working because the server-side is sending a payload with null relname/relid:

{
            "qualid": 2301593140,
            "relname": null,
            "nspname": null,
            "avg_filter": 2836.0,
            "filter_ratio": 99.96475149806133,
            "execution_count": 2837.0,
            "occurences": 1.0,
            "table_liverows": null,
            "relid": null,
            "queries": [
                "select o1_0.id,o1_0.callback_action,o1_0.dt_creation,o1_0.entity_id,o1_0.entity_name,o1_0.event_code,o1_0.exchange,o1_0.dt_last_sent,o1_0.payload,o1_0.payload_class,o1_0.routing_key,o1_0.saga_id,o1_0.sent_state,o1_0.outbox_state from saga_outbox o1_0 where o1_0.id=$1 and o1_0.outbox_state=$2 for no key update skip locked"
            ],
            "queryids": [
                "-7886546767707946110"
            ],
            "quals": [],
            "where_clause": "WHERE "
        },

This PR filters the payload to remove null relid items.
I tried this PR on our powa deployment and the "optimize this database" button seems now to work.