Mute org.elasticsearch.xpack.security.authc.service.ServiceAccountSingleNodeTests testAuthenticateWithServiceFileToken elastic#120988

Author: elasticsearchmachine

muted-tests.yml

@@ -557,3 +557,6 @@ tests:
 - class: org.elasticsearch.xpack.ml.integration.ClassificationIT
   method: testSetUpgradeMode_ExistingTaskGetsUnassigned
   issue: https://github.com/elastic/elasticsearch/issues/121928
+- class: org.elasticsearch.xpack.security.authc.service.ServiceAccountSingleNodeTests
+  method: testAuthenticateWithServiceFileToken
+  issue: https://github.com/elastic/elasticsearch/issues/120988