Remove duplicate path.repo setting in AbstractIndexCompatibilityTestCase (elastic#138264)

Author: JeremyDahlgren

qa/lucene-index-compatibility/src/javaRestTest/java/org/elasticsearch/lucene/AbstractIndexCompatibilityTestCase.java

@@ -77,7 +77,6 @@ public abstract class AbstractIndexCompatibilityTestCase extends ESRestTestCase
         .setting("path.repo", () -> REPOSITORY_PATH.getRoot().getPath())
         .setting("xpack.security.enabled", "false")
         .setting("xpack.ml.enabled", "false")
-        .setting("path.repo", () -> REPOSITORY_PATH.getRoot().getPath())
         .apply(() -> clusterConfig)
         .build();