fix: reverse potentialVictims order to reprieve higher priority pods first

[dengaosong]

What type of PR is this?

/kind bug

What this PR does / why we need it:

In SelectVictimsOnNode, potentialVictims was collected from victimsQueue.Pop() which returns lower priority pods first. This caused lower priority pods to be reprieved first, contradicting the expected behavior described in the code comment.
This fix reverses potentialVictims before the reprieve loop to ensure higher priority pods are reprieved first.

Which issue(s) this PR fixes:

Fixes #5208

Special notes for your reviewer:

The root cause is that BuildVictimsPriorityQueue uses !ssn.TaskOrderFn with negation, so Pop() returns pods in [low→high] priority order, which is opposite to the sort.Slice order [high→low].

Does this PR introduce a user-facing change?

None

Fixed victim reprieve logic in preempt action to reprieve higher priority pods first as intended.

[volcano-sh-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[volcano-sh-bot]

Welcome @dengaosong! It looks like this is your first PR to volcano-sh/volcano 🎉

[gemini-code-assist]

Code Review

This pull request refactors the preemption logic in pkg/scheduler/actions/preempt/preempt.go by removing the explicit sorting of all potential victims. Instead, it implements a manual reversal of the potentialVictims slice to maintain the correct priority order for reprieving pods, as the priority queue returns them in ascending order of priority. I have no feedback to provide.

[Copilot]

Pull request overview

Fixes victim reprieve ordering in SelectVictimsOnNode so that when attempting to add back (“reprieve”) potential victims, higher-priority pods are considered first (aligning behavior with the intended priority semantics described in #5208).

Changes:

• Removes the misleading/ineffective pre-sort of victims (and the associated k8sutil dependency).
• Reverses potentialVictims prior to the reprieve loop so reprieve proceeds from higher → lower priority.

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[Copilot]

The newly added reversal block is not gofmt-formatted (uses spaces instead of tabs and has inconsistent indentation vs the surrounding code). Please run gofmt (or adjust indentation) so the comment and for-loop align with the file’s standard formatting; this will also remove the trailing whitespace on the closing brace line.

Suggested change

	// Reverse potentialVictims to reprieve higher priority pods first.
	// potentialVictims is collected from victimsQueue.Pop() which returns lower priority first,
	// so we need to reverse it to ensure higher priority pods are reprieved first.
	for i, j := 0, len(potentialVictims)-1; i < j; i, j = i+1, j-1 {
	potentialVictims[i], potentialVictims[j] = potentialVictims[j], potentialVictims[i]
	}
	// Reverse potentialVictims to reprieve higher priority pods first.
	// potentialVictims is collected from victimsQueue.Pop() which returns lower priority first,
	// so we need to reverse it to ensure higher priority pods are reprieved first.
	for i, j := 0, len(potentialVictims)-1; i < j; i, j = i+1, j-1 {
	potentialVictims[i], potentialVictims[j] = potentialVictims[j], potentialVictims[i]
	}

[dengaosong]

Hi @k82cn @dafu-wu, could you please help approve the CI workflows to run?
This is my first contribution to this repo. Thank you!

[JesseStutler]

/ok-to-test

[JesseStutler]

You are right, but please resolve the go fmt error please @dengaosong

[JesseStutler]

Also commits should not contain like Merge branch 'master' into xxx, please use rebase to resolve it

[dengaosong]

Hi, I have resolved the issues:

1. Fixed the gofmt formatting errors
2. Rebased the branch to remove merge commits

All checks are passing now. Please take another look when you get a chance. Thanks!
@JesseStutler