test: use t.Setenv to set env vars

[Juneezee]

What type of PR is this?
/kind cleanup

What does this PR do / why we need it:

Starting from Go 1.17, we can use t.Setenv to set environment variable in test. The environment variable is automatically restored to its original value when the test and all its subtests complete. This ensures that each test does not start with leftover environment variables from previous completed tests.

Reference: https://pkg.go.dev/testing#T.Setenv

func TestFoo(t *testing.T) {
	// before
	os.Setenv(key, "new value")
	defer os.Unsetenv(key)
	
	// after
	t.Setenv(key, "new value")
}

Have you updated the necessary documentation?

• Documentation update is required by this PR.
• Documentation has been updated.

Which issue(s) this PR fixes:

Test acceptance criteria:

• Unit Test
• E2E Test

How to test changes / Special notes to the reviewer:

[openshift-ci]

@Juneezee: The label(s) kind/code-refactoring cannot be applied, because the repository doesn't have them.

In response to this:

What type of PR is this?
/kind code-refactoring

What does this PR do / why we need it:

Starting from Go 1.17, we can use t.Setenv to set environment variable in test. The environment variable is automatically restored to its original value when the test and all its subtests complete. This ensures that each test does not start with leftover environment variables from previous completed tests.

Reference: https://pkg.go.dev/testing#T.Setenv

func TestFoo(t *testing.T) {
  // before
  os.Setenv(key, "new value")
  defer os.Unsetenv(key)
  
  // after
  t.Setenv(key, "new value")
}

Have you updated the necessary documentation?

• Documentation update is required by this PR.
• Documentation has been updated.

Which issue(s) this PR fixes:

Test acceptance criteria:

• Unit Test
• E2E Test

How to test changes / Special notes to the reviewer:

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[openshift-ci]

Hi @Juneezee. Thanks for your PR.

I'm waiting for a redhat-developer 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.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[wtam2018]

/ok-to-test

[wtam2018]

/lgtm
/approve

[wtam2018]

thanks @Juneezee !

[Juneezee]

/retest

[Juneezee]

/retest

[wtam2018]

/lgtm
/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: wtam2018

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