feat: change DefaultSchedulerFilterParentLimit to 15

[gaius-qi]

Description

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.

[codecov]

Codecov Report

Merging #2932 (ea5417b) into main (f8d538b) will decrease coverage by 0.02%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2932      +/-   ##
==========================================
- Coverage   51.13%   51.11%   -0.02%     
==========================================
  Files         161      161              
  Lines       21838    21838              
==========================================
- Hits        11166    11163       -3     
- Misses      10013    10014       +1     
- Partials      659      661       +2     

Flag	Coverage Δ
Object-compatibility-e2etests	?
e2etests	?
unittests	51.11% <ø> (-0.02%)	⬇️

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

Files	Coverage Δ
scheduler/resource/task.go	82.98% <ø> (ø)

... and 1 file with indirect coverage changes