Try to fix MySQL TTL failure. (#3038)

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/storage/ttl/GeneralStorageTTL.java

@@ -32,6 +32,8 @@ public class GeneralStorageTTL implements StorageTTL {
                 return new DayTTLCalculator();
             case Month:
                 return new MonthTTLCalculator();
+            case Second:
+                return new SecondTTLCalculator();
             default:
                 return new MinuteTTLCalculator();
         }