[AMORO-4166] [Improvement]: Implement heap-based flush mechanism for SortedPosDeleteWriter to prevent OOM.

Author: slfan1989

amoro-format-iceberg/src/test/java/org/apache/amoro/io/writer/TestSortedPosDeleteWriterHeapFlush.java

@@ -18,6 +18,8 @@
 
 package org.apache.amoro.io.writer;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import org.apache.amoro.BasicTableTestHelper;
 import org.apache.amoro.TableFormat;
 import org.apache.amoro.catalog.BasicCatalogTestHelper;
@@ -42,8 +44,6 @@
 import java.util.List;
 import java.util.stream.Collectors;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
 public class TestSortedPosDeleteWriterHeapFlush extends TableTestBase {
 
   public TestSortedPosDeleteWriterHeapFlush() {