fix componentsOverride affecting default values when reconciling clusters

[xrstf]

What this PR does / why we need it:
resources.SetResourceRequirements() accidentally modified the given default requirements, which lead to more or less random effects on other clusters, depending on the reconciling order.

This seems to have been introduced in December 2019 via #4810, so 2.13+ version are affected.

Which issue(s) this PR fixes:
Fixes #5654

Does this PR introduce a user-facing change?:

Fix componentsOverride of a cluster affecting other clusters.

[kubermatic-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: xrstf

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[xrstf]

/retest

[irozzo-1A]

/lgtm

[kubermatic-bot]

LGTM label has been added.

Git tree hash: 74c8a173f151e21b728c49c8b7d3cdf5bff3994e

[xrstf]

/cherry-pick release/v2.13

[kubermatic-bot]

@xrstf: new pull request created: #5703

In response to this:

/cherry-pick release/v2.13

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[xrstf]

/cherry-pick release/v2.14

[kubermatic-bot]

@xrstf: new pull request created: #5704

In response to this:

/cherry-pick release/v2.14

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/test-infra repository.