fix(prism): Allow dictionary vector when loading lazy delta for FULL_REWRITE (facebookincubator#13094)

Summary:
Pull Request resolved: facebookincubator#13094

In full rewrite update there is no restriction on the encoding of delta
vector, so we can return the vector as it is.

Reviewed By: pedroerp

Differential Revision: D73373386

fbshipit-source-id: a004ed57a2011b61e7a00591d9c8d04cb985f6f8

Author: Yuhta

velox/dwio/dwrf/test/utils/E2EWriterTestUtil.h

@@ -113,6 +113,8 @@ class E2EWriterTestUtil {
 
   static std::vector<VectorPtr> generateBatches(VectorPtr batch);
 
+  /// NOTE: This will trigger flush before first write and disable dictionary
+  /// encoding.
   static std::function<std::unique_ptr<DWRFFlushPolicy>()>
   simpleFlushPolicyFactory(bool flushPerBatch) {
     return [flushPerBatch]() {