Reduce minAllowed values from kube-apiserver and kube-controller-manager

[ialidzhikov]

How to categorize this PR?

/area monitoring
/kind enhancement

What this PR does / why we need it:
This PR reduces minAllowed (H)VPA minAllowed values from kube-apiserver and kube-controller-manager as suggested in #9562.

Which issue(s) this PR fixes:
Part of #9562

Special notes for your reviewer:
N/A

Release note:

The kube-controller-manager's (H)VPA minAllowed memory is reduced from `100Mi` to `50Mi`. The kube-apiserver's HVPA minAllowed memory is reduced from `400M` to `200M`. 

[rfranzke]

/lgtm
/approve

[gardener-prow]

LGTM label has been added.

Git tree hash: 3bf8f6bdadad3e0fdb3f62bdc22451d0384ede19

[gardener-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rfranzke

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[gardener-prow]

@ialidzhikov: 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-gardener-e2e-kind-ha-multi-zone	9982b3d	link	unknown	/test pull-gardener-e2e-kind-ha-multi-zone

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