Add test for recomputing similar nodegroups

[rrangith]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

Related to #6926

It was suggested that first I add a test that will ensure that by default the similar nodegroup recomputation works. And then in my other PR I can add a test to ensure that if the SkipSimilarNodeGroupRecomputation field is true, then we will not recompute similar nodegroups

This adds no new functionality, just a test. It is almost identical to the existing test here. My new test just changes the expander strategy so that it returns a best option with no similar nodegroups. This will test to make sure this line correctly recomputes the similar nodegroups

Special notes for your reviewer:

You can hide whitespace changes to make it easier to review

Does this PR introduce a user-facing change?

NONE

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

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @rrangith. Thanks for your PR.

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