Adjust CIDRPool to use int32 instead of uint fields

[vasrem]

According to the API Conventions, we should not use uint type for fields.

• All public integer fields MUST use the Go int32 or Go int64 types, not int (which is ambiguously sized, depending on target platform). Internal types may use int.
• Do not use unsigned integers, due to inconsistent support across languages and libraries. Just validate that the integer is non-negative if that's the case.

In fact, issues using uint can also be observed when trying to DeepCopyJSON the object that panics with error panic: cannot deep copy uint64. (e.g. convert the object to unstructured.Unstructured and then call unstructuredObj.DeepCopy())

Upstream issue: kubernetes/kubernetes#62769

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This PR adjusts the uint fields to int32. This means that we can fully cover the IPv4 address family, but we impose limitations for the IPv6 address family since the gatewayIndex and PerNodeNetworkPrefix can go up to 2^32.

[coveralls]

coverage: 69.594% (+0.08%) from 69.514%
when pulling 2acb88f on vasrem:bugfix/use-int-instead-of-uint
into ef6ff29 on Mellanox:main.