public Set<ContentFile<?>> getDeleteFiles() {
      return deleteFiles;
    }
When splitTask has only one undersized segment file, it needs to be triggered again to
determine whether to rewrite pos. If needed, add it to rewritePosDataFiles and bin-packing
together, else reserved delete files.
amoro-format-iceberg/src/main/java/org/apache/amoro/optimizing/plan/AbstractPartitionPlan.java