Update server/src/test/java/org/elasticsearch/cluster/metadata/MetadataDeleteIndexServiceTests.java

Co-authored-by: Copilot <[email protected]>

Author: nielsbauman

server/src/test/java/org/elasticsearch/cluster/metadata/MetadataDeleteIndexServiceTests.java

@@ -199,7 +199,8 @@ public void testDeleteBackingIndexForDataStream() {
             List.of()
         );
 
-        int numIndexToDelete = randomIntBetween(1, numBackingIndices - 1) - 1;
+        // Adjusting the random index to match zero-based indexing of the list
+        int numIndexToDelete = randomIntBetween(0, numBackingIndices - 2);
 
         Index indexToDelete = before.metadata()
             .getProject(projectId)