🐛 Fix KCP remediation when node Name & etcd member Name != machine Name

[fabriziopandini]

What this PR does / why we need it:
This PR fixes a problem in KCP remediation not properly computing the targetCluster when node Name & etcd member Name != machine Name (e.g. AWS)

Backport of #4240

Which issue(s) this PR fixes:
Fixes #4239

[k8s-ci-robot]

@fabriziopandini: The following test failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-cluster-api-verify	44d737e	link	/test pull-cluster-api-verify

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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[vincepri]

/retest

[fabriziopandini]

/reopen

[k8s-ci-robot]

@fabriziopandini: Reopened this PR.

In response to this:

/reopen

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[vincepri]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: vincepri

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[vincepri]

This should be merged soon 👍

[fabriziopandini]

/milestone v0.3.x