🌱 replace reflect deepequal in bootstrap kubeadm

[DiptoChakrabarty]

What this PR does / why we need it:
replacing reflect.deepequal with cmp.Diff to which provides better diff for debugging purposes
Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #8186

This PR is for bootstrap/kubeadm will be following up with more

[sbueringer]

Let's wait with merging this until we branched v1.4 away later today

I would prefer not rushing this into this release so we can have it together with subsequent/corresponding changes in the next one

[sbueringer]

Just realized that this PR is only touching test code. I think then it doesn't matter if this PR goes in before or after we cut the release branch

[sbueringer]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 10d4dba46071bb7508ca5d3e4130e9934e533e93

[g-gaston]

/lgtm

[killianmuldoon]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: killianmuldoon

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[killianmuldoon]

/retest

[johannesfrey]

/area provider/bootstrap-kubeadm