An update to a sink shouldn't have a default value in AutoAck or Retain Ordering

[AlvaroStream]

When we try to update a sink, we receive an error like this ones:

• AutoAck cannot be altered
• Retain Ordering cannot be altered

The default value updating the sink is trying to be imposed on the sink returning the error.

Maybe --auto-ack shouldn't be allowed to be updated on the sink and set always to null. As other values like Retain Ordering or RetainKeyOrdering.

[nodece]

@AlvaroStream Thanks for your report! Please keep the same value when updating to avoid this issue. Because of to limit by the cli, we cannot provide a null value.

[nodece]

@AlvaroStream I submitted https://github.com/streamnative/pulsarctl/pull/873 to fix this.