scheduler(ticdc): fix span loss bug when split regions

[wk989898]

What problem does this PR solve?

Issue Number: close #11675

What is changed and how it works?

Some regions may not append to spans because of incorrect condition judgment of restSpans.
Make sure all regions are added to the spans before returning.

Check List

Tests

• Unit test
• Integration test

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

`None`.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-11-05 09:40:02.603179609 +0000 UTC m=+947515.442335156: ☑️ agreed by asddongmen.
• 2024-11-06 02:36:43.743218245 +0000 UTC m=+1008516.582373815: ☑️ agreed by CharlesCheung96.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: asddongmen, CharlesCheung96, sdojjy

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• OWNERS [CharlesCheung96,asddongmen,sdojjy]

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[wk989898]

/retest

[codecov]

Codecov Report

Attention: Patch coverage is 17.24138% with 24 lines in your changes missing coverage. Please review.

Project coverage is 55.1566%. Comparing base (0510cf0) to head (9f08887).
Report is 3 commits behind head on master.

Additional details and impacted files

Components	Coverage Δ
cdc	59.6044% <17.2413%> (-0.0089%)	⬇️
dm	50.0904% <ø> (+0.0018%)	⬆️
engine	53.2336% <ø> (+0.0282%)	⬆️

Flag	Coverage Δ
unit	55.1566% <17.2413%> (+0.0003%)	⬆️

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

@@               Coverage Diff                @@
##             master     #11715        +/-   ##
================================================
+ Coverage   55.1562%   55.1566%   +0.0003%     
================================================
  Files          1001       1001                
  Lines        136485     136524        +39     
================================================
+ Hits          75280      75302        +22     
- Misses        55695      55714        +19     
+ Partials       5510       5508         -2     

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #11721.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #11722.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #11723.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #11724.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #11725.