create nsswitch-conf only if missing

[longwuyuan]

What this PR does / why we need it:

• Test-runner image build failing at Dockerfile step to create nsswitch.conf
• Details are in the issue build failed for test-runner image #9338
• Maybe we don't need to create the nsswitch.conf as upstream may be doing it already
• We will know after this PR merges and cloudbuild is fired for test-runner image

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

• Expected to fix build failed for test-runner image #9338

How Has This Been Tested?

• Can only be tested in cloudbuild because problem is in cloudbuild and local-build is not the same as cloudbuild

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.
• Added Release Notes.

Does my pull request need a release note?

Any user-visible or operator-visible change qualifies for a release note. This could be a:

• CLI change
• API change
• UI change
• configuration schema change
• behavioral change
• change in non-functional attributes such as efficiency or availability, availability of a new platform
• a warning about a deprecation
• fix of a previous Known Issue
• fix of a vulnerability (CVE)

No release notes are required for changes to the following:

• Tests
• Build infrastructure
• Fixes for unreleased bugs

For more tips on writing good release notes, check out the Release Notes Handbook

create nsswitch.conf only if missing

/triage accepted
/area stabilization

/assign @tao12345666333 @rikatz

[longwuyuan]

Follow-up for #9336

[tao12345666333]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: longwuyuan, tao12345666333

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