Remove sdk.MustSortJSON from channel types Acknowledgement

[colin-axner]

Summary

Same reasoning as #3915, the sorting order should not change cross compatibility

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For Admin Use

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• Appropriate labels applied
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[expertdicer]

I don't think we can use standard encoding/json lib because the proto of Acknowledgement contains enum

message Acknowledgement {
  // response contains either a result or an error and must be non-empty
  oneof response {
    bytes  result = 21;
    string error  = 22;
  }
}