Remove reflective invocation of emitPeriodicWatermark in MixedFormatSourceReader

Author: xxubai

amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/read/hybrid/reader/MixedFormatSourceReader.java

@@ -195,19 +195,6 @@ private void emitPeriodicWatermark(SourceOutput<T> splitOutput) {
         return;
       }
 
-      try {
-        java.lang.reflect.Method method =
-            splitOutput.getClass().getDeclaredMethod("emitPeriodicWatermark");
-        method.setAccessible(true);
-        method.invoke(splitOutput);
-        return;
-      } catch (ReflectiveOperationException e) {
-        LOGGER.debug(
-            "Failed to invoke emitPeriodicWatermark on split output {}, fallback to reader output",
-            splitOutput.getClass(),
-            e);
-      }
-
       watermarkOutput.emitPeriodicWatermark();
     }
   }