Remove redundant nar hash and size setting

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>

src/libstore/binary-cache-store.cc

@@ -173,8 +173,6 @@ ref<const ValidPathInfo> BinaryCacheStore::addToStoreCommon(
 
     auto info = mkInfo(narHashSink.finish());
     auto narInfo = make_ref<NarInfo>(info);
-    narInfo->narSize = info.narSize; // FIXME needed?
-    narInfo->narHash = info.narHash; // FIXME needed?
     narInfo->compression = compression;
     auto [fileHash, fileSize] = fileHashSink.finish();
     narInfo->fileHash = fileHash;