Fix "data race" in testlogger (#9159)

* Fix data race in testlogger

* Update git_helper_for_declarative_test.go

integrations/api_repo_git_ref_test.go

@@ -12,7 +12,7 @@ import (
 )
 
 func TestAPIReposGitRefs(t *testing.T) {
-	prepareTestEnv(t)
+	defer prepareTestEnv(t)()
 	user := models.AssertExistsAndLoadBean(t, &models.User{ID: 2}).(*models.User)
 	// Login as User2.
 	session := loginUser(t, user.Name)