feat: limit concurrent image distribution jobs and add validation for IPs

[gaius-qi]

Description

This pull request makes adjustments to configuration defaults and validation rules in the job management system. The key changes include reducing the default concurrency for image distribution jobs and adding stricter validation for preheating arguments.

Configuration Updates:

• manager/service/job.go: Reduced the default value for DefaultGetImageDistributionJobConcurrentCount from 30 to 12 to optimize resource usage during image distribution jobs.

Validation Enhancements:

• manager/types/job.go: Added validation constraints to the IPs field in the PreheatArgs struct, ensuring the list contains between 1 and 100 entries (gte=1,lte=100). This prevents invalid or overly large input.

Related Issue

Motivation and Context

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[chlins]

lgtm

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 32.58%. Comparing base (94a02a2) to head (71379c3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4219   +/-   ##
=======================================
  Coverage   32.58%   32.58%           
=======================================
  Files         350      350           
  Lines       41288    41288           
=======================================
  Hits        13452    13452           
  Misses      26945    26945           
  Partials      891      891           

Flag	Coverage Δ
unittests	32.58% <ø> (ø)

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

Files with missing lines	Coverage Δ
manager/service/job.go	0.00% <ø> (ø)

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[Liam-Zhao]

LGTM