Revert "Add ICloneable support to ComponentNetworkGenerator"

[ElectroJr]

Reverts #5656

Generates invalid code when using something like

[DataField, AutoNetworkedField]
public TestClass TestField = new();

[Serializable, NetSerializable]
public sealed class TestClass : ICloneable
{
    public object Clone() => new();
}

See https://discord.com/channels/310555209753690112/900426319433728030/1341968643646423210

[deltanedas]

was good for rooting out uses of String at least