don't throw if `ADDRESS_HEADER` is absent in `adapter-node`

Describe the problem

Not all requests will have the header specified. E.g. on render.com when doing a health-check the service does an internal request. This will crash the server because the header is not present.

Describe the proposed solution

Get rid of this code: https://github.com/ivanhofer/kit/blob/export-SubmitFunction/packages/adapter-node/src/handler.js#L94-L100

This would be a breaking change as someone might rely on this error.

An option would also be to make this error throw configurable via an adapter option.

Alternatives considered

Require users to patch the getClientAddress functionality by themself.

As a workaround I currently do this in the first line of the handle function:

event.getClientAddress = () => request.headers.get('cf-connecting-ip')

Importance

would make my life easier

Additional Information

No response

Start in packages/adapter-node/src/handler.js around lines 94-100, where ADDRESS_HEADER handling is described as crashing requests without the header. Trace the handler entry point and existing getClientAddress workaround, then confirm with maintainers whether the intended behavior is removing the throw or making it configurable. Done means requests without the header no longer crash, with corresponding coverage if tests are identified.