rpc server: fix deny unsafe on RpcMethods::Auto (#5678)

Close #5677

I made a nit when I moved this code:
https://github.com/paritytech/polkadot-sdk/blob/v1.14.0-rc1/substrate/client/service/src/lib.rs#L379-#L385
in https://github.com/paritytech/polkadot-sdk/pull/4792

Thus:
 - (ip.is_loopback(), RpcMethods::Auto) -> allow unsafe
 - (!ip.is_loopback(), RpcMethods::Auto) -> deny unsafe

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Co-authored-by: ggwpez <[email protected]>