Allows for the `jsonmessage.DisplayJSONMessagesStream` function
to correctly return when the context is cancelled with the appropriate
reason (`ctx.Error()`) instead of just a nil error.
Follow-up to 30a73ff19c
Signed-off-by: Alano Terblanche <18033717+Benehiko@users.noreply.github.com>
Co-authored-by: Paweł Gronowski <pawel.gronowski@docker.com>