Rework servers load-balancer to use the WRR

Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

pkg/middlewares/metrics/metrics_test.go

@@ -60,47 +60,6 @@ func (m *collectingRetryMetrics) ServiceRetriesCounter() metrics.Counter {
 	return m.retriesCounter
 }
 
-type rwWithCloseNotify struct {
-	*httptest.ResponseRecorder
-}
-
-func (r *rwWithCloseNotify) CloseNotify() <-chan bool {
-	panic("implement me")
-}
-
-func TestCloseNotifier(t *testing.T) {
-	testCases := []struct {
-		rw                      http.ResponseWriter
-		desc                    string
-		implementsCloseNotifier bool
-	}{
-		{
-			rw:                      httptest.NewRecorder(),
-			desc:                    "does not implement CloseNotifier",
-			implementsCloseNotifier: false,
-		},
-		{
-			rw:                      &rwWithCloseNotify{httptest.NewRecorder()},
-			desc:                    "implements CloseNotifier",
-			implementsCloseNotifier: true,
-		},
-	}
-
-	for _, test := range testCases {
-		test := test
-		t.Run(test.desc, func(t *testing.T) {
-			t.Parallel()
-
-			_, ok := test.rw.(http.CloseNotifier)
-			assert.Equal(t, test.implementsCloseNotifier, ok)
-
-			rw := newResponseRecorder(test.rw)
-			_, impl := rw.(http.CloseNotifier)
-			assert.Equal(t, test.implementsCloseNotifier, impl)
-		})
-	}
-}
-
 func Test_getMethod(t *testing.T) {
 	testCases := []struct {
 		method   string