Cleanup FailureReason in scheduler - part 1

[Huang-Wei]

What type of PR is this?

/kind cleanup
/sig scheduling

What this PR does / why we need it:

Cleanup the usage of FailureReason in scheduler codebase. Now plugin returns framework.Status instead of []FailureReason.

There are still external usage of FailureReason (e.g., kubelet, daemonset controller), that will be cleaned up in the next PR, and now temporarily, some private functions (e.g., podFitsResources) have to be there to serve both external components and scheduler plugins.

Which issue(s) this PR fixes:

Part of #86353

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

/cc @ahg-g

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[k8s-ci-robot]

@Huang-Wei: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubernetes-verify	3cd6276	link	/test pull-kubernetes-verify

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[Huang-Wei]

Per offline discussion with @ahg-g, we prefer to remove FailureReason in each plugin gradually (along with its own migration PR). So closing this in favor of #86498.