[forwardport] fix: avoid http3 for dns.google and www.google.com (#593) (#594)

This commit forward ports dedd84fa7ecb09f718f6b1a9c83999cb37b34dfa.

Original commit message:

- - -

This diff changes code the release/3.11 branch to ensure we're not using dns.google and www.google.com over HTTP3. As documented in https://github.com/ooni/probe/issues/1873, since this morning (approx) these services do not support HTTP3 anymore. (I didn't bother with checking whether this issue affects _other_ Google services; I just limited my analysis to the services that we were using as part of testing.)

This patch WILL require forward porting to the master branch.

internal/cmd/oohelperd/internal/websteps/explore_test.go

@@ -5,6 +5,7 @@ import (
 	"net/url"
 	"testing"
 
+	"github.com/ooni/probe-cli/v3/internal/netxlite/quictesting"
 	"github.com/ooni/probe-cli/v3/internal/runtimex"
 )
 
@@ -84,12 +85,11 @@ func TestGetFailure(t *testing.T) {
 }
 
 func TestGetH3Success(t *testing.T) {
-	u, err := url.Parse("https://www.google.com")
-	runtimex.PanicOnError(err, "url.Parse failed for clearly good URL")
+	u := &url.URL{Scheme: "https", Host: quictesting.Domain, Path: "/"}
 	h3u := &h3URL{URL: u, proto: "h3"}
 	resp, err := explorer.getH3(h3u, nil)
 	if err != nil {
-		t.Fatal("unexpected error")
+		t.Fatal("unexpected error", err)
 	}
 	if resp == nil {
 		t.Fatal("unexpected nil response")

internal/cmd/oohelperd/internal/websteps/generate_test.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/lucas-clemente/quic-go"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
+	"github.com/ooni/probe-cli/v3/internal/netxlite/quictesting"
 	"github.com/ooni/probe-cli/v3/internal/runtimex"
 )
 
@@ -297,8 +298,7 @@ func TestGenerateHTTPSTLSFailure(t *testing.T) {
 }
 
 func TestGenerateH3(t *testing.T) {
-	u, err := url.Parse("https://www.google.com")
-	runtimex.PanicOnError(err, "url.Parse failed")
+	u := &url.URL{Scheme: "https", Host: quictesting.Domain, Path: "/"}
 	rt := &RoundTrip{
 		Proto: "h3",
 		Request: &http.Request{
@@ -309,10 +309,7 @@ func TestGenerateH3(t *testing.T) {
 		},
 		SortIndex: 0,
 	}
-	endpointMeasurement := generator.GenerateH3Endpoint(context.Background(), rt, "173.194.76.103:443")
-	if err != nil {
-		t.Fatal("unexpected err")
-	}
+	endpointMeasurement := generator.GenerateH3Endpoint(context.Background(), rt, quictesting.Endpoint("443"))
 	if endpointMeasurement == nil {
 		t.Fatal("unexpected nil urlMeasurement")
 	}