Unmute test that was already fixed

Author: ioanatia

muted-tests.yml

@@ -465,9 +465,6 @@ tests:
 - class: org.elasticsearch.xpack.ml.integration.RevertModelSnapshotIT
   method: testRevertModelSnapshot
   issue: https://github.com/elastic/elasticsearch/issues/132733
-- class: org.elasticsearch.xpack.esql.qa.single_node.GenerativeForkIT
-  method: test {csv-spec:lookup-join.MvJoinKeyFromRowExpanded}
-  issue: https://github.com/elastic/elasticsearch/issues/132778
 - class: org.elasticsearch.gradle.internal.transport.TransportVersionManagementPluginFuncTest
   method: definitions have primary ids which cannot change
   issue: https://github.com/elastic/elasticsearch/issues/132788