Prevent flakiness in instance groups controller test

[anyush]

This test originally was added to test that creation/update/deletion of multiple nodes won't cause multiple IG controller resyncs: #2523

However as soon as node created/updated/deleted controller tries to take event out of the queue and process it, therefore if 2 actions performed one after another there is still a possibility that event processing will start before second action pushes event on the queue, which will increase len(fakeManager.syncedNodes) value.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: anyush
Once this PR has been reviewed and has the lgtm label, please assign aojea for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

Hi @anyush. 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.

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-sigs/prow repository.

[TortillaZHawaii]

/ok-to-test