Use consistent type port and replication state

[dbussink]

These are used as int32 in the protobuf (and enum maps to int32 for replication state). This means we should also keep using int32 internally if easily possible.

Related Issue(s)

Part of #12216

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• "Backport to:" labels have been added if this change should be back-ported
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• Documentation was added or is not required

[vitess-bot]

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[rsajwani]

LGTM. There is a test failure which doesn't look related to this change but still kindly make sure if passes before you push.

[dbussink]

LGTM. There is a test failure which doesn't look related to this change but still kindly make sure if passes before you push.

That's fixed in #12253