Fix conformance test race condition (#3350)

We had two tests that used an HTTPRoute called "http-route-4" which
caused flaky tests because the first test's delete can (and sometimes
does) happen after the second test's create, which means that the
order of operations was:

1. create http-route-4
1. run first test
1. cleanup first test - queue a delete of http-route-4
1. set up second test - what should have been a create of http-route-4 becomes an update
1. delete from first test deletes http-route-4
1. second test fails

conformance/tests/gateway-with-attached-routes-with-port-8080.yaml

@@ -26,7 +26,7 @@ spec:
 apiVersion: gateway.networking.k8s.io/v1
 kind: HTTPRoute
 metadata:
-  name: http-route-4
+  name: http-route-4-port-8080
   namespace: gateway-conformance-infra
 spec:
   parentRefs: