Prevent overflowing memory limits

[norbertcyran]

What type of PR is this?

/kind bug

What this PR does / why we need it:

This PR defaults memory limits to sane default in case of int64 overflow. Overflow is possible, since we multiply the values provided via the flag by GiB (1024^3). The issue has been discovered with the new resource quotas implementation.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: norbertcyran
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[k8s-ci-robot]

Hi @norbertcyran. Thanks for your PR.

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[jackfrancis]

I'd love to see some UTs for these overflow conditions