[release-1.5] 🐛 clusterctl: validate no objects exist from CRDs before deleting them

[sbueringer]

What this PR does / why we need it:
Manual cherry-pick of #9808

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 #

/assign @chrischdi @fabriziopandini

[k8s-ci-robot]

@sbueringer: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-apidiff-release-1-5	dda8d01	link	false	/test pull-cluster-api-apidiff-release-1-5

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[chrischdi]

/lgtm

[chrischdi]

/area clusterctl

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 5c2720296c2642b367146201fc98096dbc460b0c

[sbueringer]

/approve

[k8s-ci-robot]

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This pull-request has been approved by: sbueringer

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