Handle already registered NNS hashed correctly

[carpawell]

If contract hashes are not equal to the expected ones we just call AddRecord that seems like not expected action in our deploys but anyway.

neofs-node/cmd/neofs-adm/internal/modules/morph/initialize_nns.go

Lines 168 to 179 in 17059b3

	if s == expectedHash {
	return nil, nil
	}
	}
	emit.AppCall(bw.BinWriter, nnsHash, "addRecord", callflag.All,
	domain, int64(nns.TXT), expectedHash.StringLE())
	if bw.Err != nil {
	panic(bw.Err)
	}
	return bw.Bytes(), nil

[fyrchik]

I think we can remove the logic of checking and just set the record. The checking was done to avoid spending more GAS than needed, but in on-prem installations this is not a problem. Also, the code should become much simpler.