scheduler: support changing batch for slow score scheduler

[rleungx]

What problem does this PR solve?

Issue Number: Close #xxx

What is changed and how does it work?

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

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[ti-chi-bot]

[FORMAT CHECKER NOTIFICATION]

Notice: To remove the do-not-merge/needs-linked-issue label, please provide the linked issue number on one line in the PR body, for example: Issue Number: close #123 or Issue Number: ref #456, multiple issues should use full syntax for each issue and be separated by a comma, like: Issue Number: close #123, ref #456.

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[codecov]

Codecov Report

Attention: Patch coverage is 51.85185% with 13 lines in your changes missing coverage. Please review.

Project coverage is 76.20%. Comparing base (1e76110) to head (a6d91be).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8888   +/-   ##
=======================================
  Coverage   76.20%   76.20%           
=======================================
  Files         461      461           
  Lines       70431    70471   +40     
=======================================
+ Hits        53669    53700   +31     
- Misses      13407    13415    +8     
- Partials     3355     3356    +1     

Flag	Coverage Δ
unittests	76.20% <51.85%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[rleungx]

/retest

[rleungx]

/retest