'Consortiums' should be nil since system channel is no longer supported in Fabric v3.x

### Description

I was running the [devmode setup](https://hyperledger-fabric.readthedocs.io/en/latest/peer-chaincode-devmode.html) and the following warning appeared:
`'Consortiums' should be nil since system channel is no longer supported in Fabric v3.x`
I guess it should be fixed, as the main branch contains already pre v3.x stuff? If its safe to just remove the consortium entry, I'll be happy to do it.

### Steps to reproduce

```
$ configtxgen -profile SampleDevModeSolo -channelID syschannel -outputBlock genesisblock -configPath $FABRIC_CFG_PATH -outputBlock "$(pwd)/sampleconfig/genesisblock"
2024-03-28 13:21:08.452 CET 0001 INFO [common.tools.configtxgen] main -> Loading configuration
2024-03-28 13:21:08.467 CET 0002 INFO [common.tools.configtxgen.localconfig] completeInitialization -> orderer type: solo
2024-03-28 13:21:08.467 CET 0003 INFO [common.tools.configtxgen.localconfig] Load -> Loaded configuration: /fabric/sampleconfig/configtx.yaml
2024-03-28 13:21:08.474 CET 0004 INFO [common.tools.configtxgen] doOutputBlock -> Generating genesis block
2024-03-28 13:21:08.474 CET 0005 ERRO [common.tools.configtxgen] doOutputBlock -> Warning: 'Consortiums' should be nil since system channel is no longer supported in Fabric v3.x
2024-03-28 13:21:08.475 CET 0006 INFO [common.tools.configtxgen] doOutputBlock -> Writing genesis block
```