Remove value judgements from test case messages

[mattias-p]

Today we have few test case messages that include value judgements such as "Unexpectedly ..." and "which is not OK". Test case messages should plainly state facts. Value judgements should instead be conveyed by the severity level assigned to the message. In DNSCheck we had longer explanations of the test messages. Unfortunately we don't have such explanations in Zonemaster, but if we did that would be a good place for a more nuanced description of the severity.

[matsduf]

Since we tend to specify more into the specifications the issue should maybe be as zonemaster/zonemaster issue.

Should the test case specification template be updated?

It would also be helpful if this issue lists those messages (message tags) that are in question.