remove redundant code

Signed-off-by: tyltr <tylitianrui@126.com>

discovery/legacymanager/manager_test.go

@@ -1091,7 +1091,6 @@ func TestCoordinationWithReceiver(t *testing.T) {
 	}
 
 	for _, tc := range testCases {
-		tc := tc
 		t.Run(tc.title, func(t *testing.T) {
 			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 			defer cancel()