*: add scatter_finish_region in split result

[crazycs520]

What problem does this PR solve?

Add scatter_finish_region in split result.

before:

test> split table t between (0) and (100000) regions 4;
+--------------------+----------------------+
| TOTAL_SPLIT_REGION | SCATTER_FINISH_RATIO |
+--------------------+----------------------+
| 3                  | 1.0                  |
+--------------------+----------------------+

This PR:

test> split table t between (0) and (100000) regions 4;
+--------------------+----------------------+-----------------------+
| TOTAL_SPLIT_REGION | SCATTER_FINISH_RATIO | SCATTER_FINISH_REGION |
+--------------------+----------------------+-----------------------+
| 3                  | 1.0                  | 3                     |
+--------------------+----------------------+-----------------------+

What is changed and how it works?

Check List

Tests

• Unit test

Code changes

• Has exported function/method change

Side effects

Related changes

• Need to cherry-pick to the release branch

[sre-bot]

Thanks for your PR.
This PR will be closed by bot because you already had 2 opened PRs, close or merge them before submitting a new one.
#11721 , #11795

[codecov]

Codecov Report

Merging #11805 into master will decrease coverage by 0.1344%.
The diff coverage is 100%.

@@              Coverage Diff               @@
##             master   #11805        +/-   ##
==============================================
- Coverage   81.6144%   81.48%   -0.1345%     
==============================================
  Files           435      435                
  Lines         94928    93807      -1121     
==============================================
- Hits          77475    76434      -1041     
+ Misses        11968    11899        -69     
+ Partials       5485     5474        -11

[sre-bot]

Thanks for your PR.
This PR will be closed by bot because you already had 2 opened PRs, close or merge them before submitting a new one.
#11702 , #12016