Fix "data race" in testlogger (#9159)

* Fix data race in testlogger

* Update git_helper_for_declarative_test.go

integrations/api_fork_test.go

@@ -12,7 +12,7 @@ import (
 )
 
 func TestCreateForkNoLogin(t *testing.T) {
-	prepareTestEnv(t)
+	defer prepareTestEnv(t)()
 	req := NewRequestWithJSON(t, "POST", "/api/v1/repos/user2/repo1/forks", &api.CreateForkOption{})
 	MakeRequest(t, req, http.StatusUnauthorized)
 }