Kraken: Move UpdateTradablePairs to a test

This should not happen in TestMain just because it's a requirement for
most tests. It should just be a non-parallel early test.
That allows unit tests to run quickly without calling it, and allows
proper clear failures

exchanges/kraken/kraken_test.go

@@ -60,13 +60,14 @@ func TestMain(m *testing.M) {
 	if err != nil {
 		log.Fatal(err)
 	}
-	err = k.UpdateTradablePairs(context.Background(), true)
-	if err != nil {
-		log.Fatal(err)
-	}
 	os.Exit(m.Run())
 }
 
+func TestUpdateTradablePairs(t *testing.T) {
+	err := k.UpdateTradablePairs(context.Background(), true)
+	assert.NoError(t, err, "Update tradable Pairs should not error")
+}
+
 func TestStart(t *testing.T) {
 	t.Parallel()
 	err := k.Start(context.Background(), nil)