fix: don't panic on shutdown for nil nodepools for logging budgets

[njtran]

Fixes #N/A

Description
On shutdown, we were getting panics since we weren't returning after a failed nodePool.List call.

How was this change tested?
make presubmit

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[jonathan-innis]

LGTM 🚀

[jonathan-innis]

Discussed offline. I think the method signature should just be ValdiateBudgets() error so that we are less likely to miss error returns like this

[jonathan-innis]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jonathan-innis, njtran

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[coveralls]

Pull Request Test Coverage Report for Build 7219277746

• 0 of 2 (0.0%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.05%) to 79.891%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/controllers/disruption/controller.go	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/controllers/disruption/controller.go	1	72.67%
pkg/test/cachesyncingclient.go	2	78.13%
pkg/test/expectations/expectations.go	2	95.01%

Totals
Change from base Build 7219068882:	-0.05%
Covered Lines:	7648
Relevant Lines:	9573

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💛 - Coveralls