Unmute testWatcherWithApiKey (#126502)

Resolves: https://github.com/elastic/elasticsearch/issues/124159

muted-tests.yml

@@ -261,9 +261,6 @@ tests:
 - class: org.elasticsearch.env.NodeEnvironmentTests
   method: testIndexCompatibilityChecks
   issue: https://github.com/elastic/elasticsearch/issues/124388
-- class: org.elasticsearch.xpack.restart.FullClusterRestartIT
-  method: testWatcherWithApiKey {cluster=UPGRADED}
-  issue: https://github.com/elastic/elasticsearch/issues/124159
 - class: org.elasticsearch.multiproject.test.CoreWithMultipleProjectsClientYamlTestSuiteIT
   method: test {yaml=data_stream/190_failure_store_redirection/Redirect ingest failure in data stream to failure store}
   issue: https://github.com/elastic/elasticsearch/issues/124518