hardens integration serviceaccount tests

[p0lyn0mial]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

the serviceAccountController controller used by the tests must wait for the caches to sync
since the tests don't check /readyz there is no way
the tests can tell it is safe to call the server and requests won't be rejected

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

Please note that we're already in Test Freeze for the release-1.24 branch. This means every merged PR has to be cherry-picked into the release branch to be part of the upcoming v1.24.0 release.

[k8s-ci-robot]

@p0lyn0mial: This issue is currently awaiting triage.

If a SIG or subproject determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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[p0lyn0mial]

/assign @aojea @wojtek-t

[wojtek-t]

/lgtm
/approve

Thanks!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: p0lyn0mial, wojtek-t

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• test/OWNERS [wojtek-t]

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[k8s-triage-robot]

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/retest