fix 1336 with corrected start and stop annotations

[willr3]

Should generate a corrected openapi.yaml. We should also look at testing the generated openapi.yaml with all endpoints?

closes: #1336

[stalep]

We should have a look at how we format date/time in Horreum. In TestService.listLabelValues we use strings as the type, but we accept either iso-like or epoch. I think the intention was to default to that, but it has not been communicated well.

[willr3]

TestService.listLabelValues supports different time formats for the before and after query parameters to make it easier for users to request data from Horreum. The issue this addresses is how we describe the data that Horreum provides.

When Horreum encodes an Instant into json it is currently encoded as a Long but the annotations told openapi to create an openapi.yaml that claims the values will be an ISO style string. The PR changes the annotations to match the data type Horreum is already using.

We can discuss if Long or an ISO String is more appropriate for integration with other tools but for now this PR is a bug fix for incorrect annotations.

[webbnh]

Looks good to me.

[johnaohara]

This PR is missing the changes to openapi.yaml. Please can we ensure that if we change the openapi annotations, that the corresponding generated openapi.yaml is also checked in with the PR otherwise what we publish on the website is out of sync with the actual API