Resolve lint errors causing CI to break

[tzifudzi]

What type of PR is this?

Cleanup

What this PR does / why we need it:

It resolves lint errors causing new PRs to fail lint checks.

Changes are

• making minor changes to resolve lint errors e.g. unnecessary use of fmt.Sprintf
• removing linters which are no longer actively maintained
• disabling depguard as a linter

See additinoal info section for more regarding why the below changes were made

Which issue(s) this PR fixes:

#78

Additional info

Lint errors are failing with the following errors. See example failing Github Actions in PR #81

pkg/testcases/context_test.go:22:2: import 'sigs.k8s.io/windows-operational-readiness/pkg/flags' is not allowed from list 'Main' (depguard)
        "sigs.k8s.io/windows-operational-readiness/pkg/flags"

To resolve the above errors, I disabled depguard because it has a known breaking issue. See golangci/golangci-lint#3906 fore more. For the meantime, we will simply remove the dependency until the issue is resolved. In summary, lint checks are failing because depguard used to allow all dependencies by default, but its v2 release inverts that logic to deny by default. We do not have control over the allow list because it is abstracted by golangci-lint

Other changes include removing linters which are no longer actively maintained

WARN [runner] The linter 'varcheck' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused. 
WARN [runner] The linter 'structcheck' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused. 
WARN [runner] The linter 'deadcode' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused. 
WARN [runner] The linter 'ifshort' is deprecated (since v1.48.0) due to: The repository of the linter has been deprecated by the owner. 

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: tzifudzi
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[k8s-ci-robot]

Hi @tzifudzi. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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