Unmute MvJoinKeyFromRow (elastic#125128)

Closes elastic#124951

Author: ivancea

muted-tests.yml

@@ -360,9 +360,6 @@ tests:
 - class: org.elasticsearch.datastreams.lifecycle.DataStreamLifecycleServiceIT
   method: testErrorRecordingOnRetention
   issue: https://github.com/elastic/elasticsearch/issues/124950
-- class: org.elasticsearch.xpack.esql.qa.single_node.EsqlSpecIT
-  method: test {lookup-join.MvJoinKeyFromRow SYNC}
-  issue: https://github.com/elastic/elasticsearch/issues/124951
 - class: org.elasticsearch.xpack.esql.action.CrossClusterAsyncQueryStopIT
   method: testStopQueryLocalNoRemotes
   issue: https://github.com/elastic/elasticsearch/issues/124959