schedulers: speed up the balance-region-scheduler by decrease influence amp. (#5254)

[ti-chi-bot]

This is an automated cherry-pick of #5254

What problem does this PR solve?

Issue Number: Close #4990

What is changed and how does it work?

schedulers: speed up the balance-region-scheduler by decrease influence amp

Check List

Tests

• Unit test
• Manual test (add detailed scripts or steps below)

100 TIKV simulator, 10GB region size:

current

operator:

region count:

master

4 TIKV, 1GB region size in real cluster:

current

region count:

master

Code changes

Side effects

Related changes

• Need to cherry-pick to the release branch

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• nolouch

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[codecov]

Codecov Report

Merging #5320 (a541f71) into release-6.1 (cf931ec) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head a541f71 differs from pull request most recent head 680c1bc. Consider uploading reports for the commit 680c1bc to get more accurate results

@@             Coverage Diff              @@
##           release-6.1    #5320   +/-   ##
============================================
  Coverage        75.47%   75.47%           
============================================
  Files              307      307           
  Lines            30353    30354    +1     
============================================
+ Hits             22908    22910    +2     
  Misses            5452     5452           
+ Partials          1993     1992    -1     

Flag	Coverage Δ
unittests	75.47% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
server/schedulers/utils.go	94.02% <ø> (ø)
server/grpc_service.go	52.73% <100.00%> (+0.13%)	⬆️
server/id/id.go	76.19% <0.00%> (-4.77%)	⬇️
server/schedulers/random_merge.go	60.00% <0.00%> (-3.34%)	⬇️
server/region_syncer/server.go	83.15% <0.00%> (-3.27%)	⬇️
server/tso/allocator_manager.go	60.56% <0.00%> (-2.00%)	⬇️
server/schedule/operator/step.go	74.07% <0.00%> (-1.02%)	⬇️
server/cluster/coordinator.go	70.63% <0.00%> (-0.83%)	⬇️
server/cluster/cluster.go	83.59% <0.00%> (-0.28%)	⬇️
... and 9 more

---

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[nolouch]

ptal @lhy1024

[bufferflies]

/merge

[ti-chi-bot]

@bufferflies: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: a541f71