[Fix](topn) fix wrong nullable cast for RowId column and use heapsort…

[eldenmoon]

…er for two phase read

convert_nullable_flags does not contain nullable info for RowID column, but valid_column_ids contain RowID column, nullable falg will be undefined for RowID column

Proposed changes

Issue Number: close #16398

Problem summary

Describe your changes.

Checklist(Required)

1. Does it affect the original behavior:
   • Yes
   • No
   • I don't know
2. Has unit tests been added:
   • Yes
   • No
   • No Need
3. Has document been added or modified:
   • Yes
   • No
   • No Need
4. Does it need to update dependencies:
   • Yes
   • No
5. Are there any changes that cannot be rolled back:
   • Yes (If Yes, please explain WHY)
   • No

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[hello-stephen]

TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 34.29 seconds
load time: 484 seconds
storage size: 17170906135 Bytes
https://doris-community-test-1308700295.cos.ap-hongkong.myqcloud.com/tmp/20230203085920_clickbench_pr_90116.html

[yiguolei]

LGTM