server: TestTelemetrySQLStatsIndependence uses test reg server

Previously, this test hit the real registration server which caused
goroutine leaks when the reg server was unavailable.

The test now creates a test reg server to handle the stats calls.
The test is no longer skipped.

Resolves #63851

Release note: None

pkg/server/stats_test.go

@@ -26,8 +26,8 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/sqlstats"
 	"github.com/cockroachdb/cockroach/pkg/sql/tests"
 	"github.com/cockroachdb/cockroach/pkg/testutils"
+	"github.com/cockroachdb/cockroach/pkg/testutils/diagutils"
 	"github.com/cockroachdb/cockroach/pkg/testutils/serverutils"
-	"github.com/cockroachdb/cockroach/pkg/testutils/skip"
 	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
@@ -39,13 +39,19 @@ func TestTelemetrySQLStatsIndependence(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
 
-	// This test fails if the central reporting server from CRL
-	// breaks. It should be improved to customize the reporting URL and
-	// mock the registration collector with an in-memory server.
-	skip.WithIssue(t, 63851)
-
 	ctx := context.Background()
 	params, _ := tests.CreateTestServerParams()
+
+	r := diagutils.NewServer()
+	defer r.Close()
+
+	url := r.URL()
+	params.Knobs.Server = &TestingKnobs{
+		DiagnosticsTestingKnobs: diagnostics.TestingKnobs{
+			OverrideReportingURL: &url,
+		},
+	}
+
 	s, sqlDB, _ := serverutils.StartServer(t, params)
 	defer s.Stopper().Stop(ctx)