Applies_to: Don't show base version for the "Unavailable" lifecycle status

[florent-leborgne]

When "unavailable" is paired with a specific version, this is fine as sometimes writers need to explicitly convey that a feature wasn't available in certain former versions, for example if a feature is added in 9.2.

On the other hand, when unavailable is used with no version, it is mostly to mean that the feature is not available at all for a product. In that case, we should not render the base version as we do by default with other statuses.

• stack: unavailable 9.0-9.2 is valid and the badge should show "Unavailable 9.0-9.2"
• stack: unavailable is valid and the badge should show "Unavailable" instead of "Unavailable 9.0+"

[shainaraskas]

this will be covered by #2634 + #2630