fix: use exponential backoff policy to listen on nginx.StatusPort in unit test cases

[tokers]

What this PR does / why we need it:

Currently, unit test cases are run parallelly, however, some test cases might listen on the Nginx status port (10246) simultaneously, which broken their running.

In this Pull Request, an exponential backoff policy is applied in these unit test cases, considering these test cases won't run continuously for a long while, it should be effective.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

#7127

How Has This Been Tested?

Checklist:

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

[k8s-ci-robot]

Hi @tokers. Thanks for your PR.

I'm waiting for a kubernetes 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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[tao12345666333]

/ok-to-test

[tao12345666333]

/assign

[tao12345666333]

/retest

[tao12345666333]

It's green.

/lgtm

[rikatz]

/approve

Thank you!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rikatz, tao12345666333, tokers

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