*: persist region leader

[rleungx]

What problem does this PR solve?

Issue Number: ref #7897.

What is changed and how does it work?

Before:

After:

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 85.29412% with 5 lines in your changes missing coverage. Please review.

Project coverage is 77.38%. Comparing base (199b017) to head (4371db4).
Report is 54 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8238      +/-   ##
==========================================
+ Coverage   77.26%   77.38%   +0.11%     
==========================================
  Files         471      471              
  Lines       61346    61346              
==========================================
+ Hits        47401    47474      +73     
+ Misses      10383    10311      -72     
+ Partials     3562     3561       -1     

Flag	Coverage Δ
unittests	77.38% <85.29%> (+0.11%)	⬆️

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[ti-chi-bot]

PR needs rebase.

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[nolouch]

Do we still consider this?