Tests were running 4 times due to multiple times the TestingT{} was being called

Calling multiple times TestingT{} will hook up runner for Suites for that many times
which would lead to repeated running tests.

Fix it by only initializing it once for all the Suites

pkg/server/api_donut_cache_test.go

@@ -22,7 +22,6 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"testing"
 
 	"encoding/xml"
 	"net/http"
@@ -33,8 +32,6 @@ import (
 	"github.com/minio/minio/pkg/server/api"
 )
 
-func TestAPIDonutCache(t *testing.T) { TestingT(t) }
-
 type MyAPIDonutCacheSuite struct {
 	root string
 }