[Improvement] Clean up Scheduler logic

[ruanwenjun]

Purpose of the pull request

• Refactor scheduler code
• Remove unused code

Brief change log

Verify this pull request

This pull request is code cleanup without any test coverage.

(or)

This pull request is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(or)

If your pull request contain incompatible change, you should also add it to docs/docs/en/guide/upgrede/incompatible.md

[codecov-commenter]

Codecov Report

Attention: 118 lines in your changes are missing coverage. Please review.

Comparison is base (df656a7) 37.89% compared to head (a437bda) 37.93%.

❗ Current head a437bda differs from pull request most recent head dc5a319. Consider uploading reports for the commit dc5a319 to get more accurate results

Files	Patch %	Lines
...api/service/impl/ProcessDefinitionServiceImpl.java	15.55%	38 Missing ⚠️
...heduler/api/service/impl/SchedulerServiceImpl.java	0.00%	38 Missing ⚠️
...nscheduler/service/process/ProcessServiceImpl.java	6.66%	13 Missing and 1 partial ⚠️
...che/dolphinscheduler/api/python/PythonGateway.java	0.00%	11 Missing ⚠️
...er/api/service/impl/TaskDefinitionServiceImpl.java	12.50%	7 Missing ⚠️
...er/api/controller/ProcessDefinitionController.java	37.50%	4 Missing and 1 partial ⚠️
...i/service/impl/ProcessTaskRelationServiceImpl.java	16.66%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                dev   #15198      +/-   ##
============================================
+ Coverage     37.89%   37.93%   +0.03%     
+ Complexity     4661     4638      -23     
============================================
  Files          1281     1281              
  Lines         44861    44600     -261     
  Branches       4864     4814      -50     
============================================
- Hits          17000    16917      -83     
+ Misses        26004    25831     -173     
+ Partials       1857     1852       -5     

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[caishunfeng]

NIP, I think it's better to check DAG dto.

[ruanwenjun]

I added comment on this method, and will use another pr to add a public method for check if the dag is validated.

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
7 Code Smells

13.3% Coverage
0.7% Duplication

Catch issues before they fail your Quality Gate with our IDE extension SonarLint

[caishunfeng]

LGTM