Unmute IndexUpgradeIT tests

The errors were caused because release tests would use a copy of
the public key that was formatted differently. The change to the
public key format was introduced in [1].

Release tests Jenkins job has now been updated to use the correct
key format depending on the branch they run on [2]

Closes #30430

[1] #30251
[2] elastic/infra#4944

x-pack/plugin/upgrade/src/test/java/org/elasticsearch/xpack/upgrade/IndexUpgradeIT.java

@@ -5,7 +5,6 @@
  */
 package org.elasticsearch.xpack.upgrade;
 
-import org.apache.lucene.util.LuceneTestCase.AwaitsFix;
 import org.elasticsearch.Build;
 import org.elasticsearch.ElasticsearchSecurityException;
 import org.elasticsearch.action.search.SearchResponse;
@@ -31,7 +30,6 @@
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.core.IsEqual.equalTo;
 
-@AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/30430")
 public class IndexUpgradeIT extends IndexUpgradeIntegTestCase {
 
     @Before