[CI] Unmute UpgradeClusterClientYamlTestSuiteIT (#116169)

Related to #115170

Author: davidkyle

muted-tests.yml

@@ -289,8 +289,6 @@ tests:
 - class: org.elasticsearch.xpack.inference.DefaultEndPointsIT
   method: testInferDeploysDefaultE5
   issue: https://github.com/elastic/elasticsearch/issues/115361
-- class: org.elasticsearch.upgrades.UpgradeClusterClientYamlTestSuiteIT
-  issue: https://github.com/elastic/elasticsearch/issues/115170
 - class: org.elasticsearch.xpack.inference.rest.ServerSentEventsRestActionListenerTests
   method: testNoStream
   issue: https://github.com/elastic/elasticsearch/issues/114788