zoekt-archive-index: disable log in tests unless verbose

Was running this test a lot and the log output was spammy.

Change-Id: I8cb4fe7ad9372abbb1cf9f46edddeadb2584b55b
diff --git a/cmd/zoekt-archive-index/e2e_test.go b/cmd/zoekt-archive-index/e2e_test.go
index 6456f41..c4e16a2 100644
--- a/cmd/zoekt-archive-index/e2e_test.go
+++ b/cmd/zoekt-archive-index/e2e_test.go
@@ -6,9 +6,11 @@
 	"compress/gzip"
 	"context"
 	"errors"
+	"flag"
 	"fmt"
 	"io"
 	"io/ioutil"
+	"log"
 	"os"
 	"strings"
 	"testing"
@@ -19,6 +21,14 @@
 	"github.com/google/zoekt/shards"
 )
 
+func TestMain(m *testing.M) {
+	flag.Parse()
+	if !testing.Verbose() {
+		log.SetOutput(ioutil.Discard)
+	}
+	os.Exit(m.Run())
+}
+
 func writeArchive(w io.Writer, format string, files map[string]string) (err error) {
 	if format == "zip" {
 		zw := zip.NewWriter(w)