Add Transform associated indices (#69493)

These somehow got dropped from the initial Feature States PR, so this
commit adds them again.

x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/Transform.java

@@ -121,6 +121,8 @@
 import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
+import static org.elasticsearch.xpack.core.transform.transforms.persistence.TransformInternalIndexConstants.AUDIT_INDEX_PATTERN;
+
 public class Transform extends Plugin implements SystemIndexPlugin, PersistentTaskPlugin {
 
     public static final String NAME = "transform";
@@ -371,6 +373,10 @@ public Collection<SystemIndexDescriptor> getSystemIndexDescriptors(Settings sett
         }
     }
 
+    @Override public Collection<String> getAssociatedIndexPatterns() {
+        return List.of(AUDIT_INDEX_PATTERN);
+    }
+
     @Override
     public String getFeatureName() {
         return "transform";