[YUNIKORN-2616] Remove unused bool return from PreemptionPredicates()

[ryankert01]

What is this PR for?

The predicate manager method PreemptionPredicates() returns two values an int and boolean. The boolean is false if the integer is -1 and true for 0 or llarger. There is no need for the boolean as the -1 already indicates the same

What type of PR is it?

• - Bug Fix
• - Improvement
• - Feature
• - Documentation
• - Hot Fix
• - Refactoring

Todos

• - Task

What is the Jira issue?

https://issues.apache.org/jira/browse/YUNIKORN-2616

How should this be tested?

Github CI

Screenshots (if appropriate)

Questions:

• - The licenses files need update.
• - There is breaking changes for older versions.
• - It needs documentation.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 67.34%. Comparing base (0c90ea5) to head (c0d964e).
Report is 1 commits behind head on master.

Files	Patch %	Lines
pkg/plugin/predicates/predicate_manager.go	75.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #841   +/-   ##
=======================================
  Coverage   67.34%   67.34%           
=======================================
  Files          70       70           
  Lines        7598     7598           
=======================================
  Hits         5117     5117           
  Misses       2269     2269           
  Partials      212      212           

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[chenyulin0719]

Some minor changes.

[chenyulin0719]

+1 LGTM

[pbacsko]

+1