index not found exception response as emptylist for correlations

Signed-off-by: Riya Saxena <[email protected]>

src/main/java/org/opensearch/securityanalytics/correlation/alert/CorrelationAlertService.java

@@ -41,7 +41,6 @@
 import org.opensearch.securityanalytics.action.AckCorrelationAlertsResponse;
 import org.opensearch.securityanalytics.action.GetCorrelationAlertsResponse;
 import org.opensearch.securityanalytics.util.CorrelationIndices;
-import org.opensearch.securityanalytics.util.CorrelationRuleIndices;
 
 import java.io.IOException;
 import java.time.Instant;