pkg: use individual package for splitter and scatter

[rleungx]

What problem does this PR solve?

Issue Number: Ref #5839.

What is changed and how does it work?

Just refactor to make the dependency clearer.

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• nolouch

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[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (09dcabe) 74.72% compared to head (4fe5f3c) 74.72%.

❗ Current head 4fe5f3c differs from pull request most recent head 41c52dc. Consider uploading reports for the commit 41c52dc to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6552   +/-   ##
=======================================
  Coverage   74.72%   74.72%           
=======================================
  Files         415      416    +1     
  Lines       42573    42581    +8     
=======================================
+ Hits        31811    31819    +8     
+ Misses       7962     7956    -6     
- Partials     2800     2806    +6     

Flag	Coverage Δ
unittests	74.72% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
pkg/schedule/metrics.go	100.00% <ø> (ø)
pkg/schedule/scatter/region_scatterer.go	79.10% <ø> (ø)
pkg/schedule/splitter/region_splitter.go	69.52% <ø> (ø)
server/cluster/cluster.go	80.91% <ø> (-0.47%)	⬇️
pkg/schedule/coordinator.go	72.85% <100.00%> (+0.12%)	⬆️
pkg/schedule/scatter/metrics.go	100.00% <100.00%> (ø)

... and 39 files with indirect coverage changes

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[nolouch]

/merge

[ti-chi-bot]

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

/run-all-tests

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[ti-chi-bot]

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

Commit hash: eba0a98

[rleungx]

/merge

[ti-chi-bot]

@rleungx: 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: 41c52dc