NPE fix for IndexController#getPhysicalTableName (#8397)

oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/base/IndexController.java

@@ -88,7 +88,7 @@ public enum IndexController {
         public static final String METRIC_TABLE_NAME = "metric_table";
 
         public static String getPhysicalTableName(String logicName) {
-            return Optional.of(LOGIC_INDICES_CATALOG.get(logicName)).orElse(logicName);
+            return Optional.ofNullable(LOGIC_INDICES_CATALOG.get(logicName)).orElse(logicName);
         }
 
         public static void registerRelation(String logicName, String physicalName) {