Remove ovn4nfv support

[floryut]

What type of PR is this?
/kind cleanup

What this PR does / why we need it:
ovn4nfv last update was 1 year and a half ago.. in kubernetes time it's way too much.

Which issue(s) this PR fixes:
None

Special notes for your reviewer:
WDYT ?

Does this PR introduce a user-facing change?:

Remove ovn4nfv support

[k8s-ci-robot]

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[cristicalin]

Sad to loose functionality but this particular project looks more like a vendor PoC rather than anything aimed for production.

👍 from me, I'm actually curious if anyone is actively using it and would like to step up and maintain it.

[EppO]

/lgtm

I like spring cleaning :)

[electrocucaracha]

Sad to loose functionality but this particular project looks more like a vendor PoC rather than anything aimed for production.

👍 from me, I'm actually curious if anyone is actively using it and would like to step up and maintain it.

The only person that I know using it is @ritusood for the EMCO project