Translation Status page shows `Generation date:` as current date and time when loading

[cylewaitforit]

Describe the bug

When the translation data is unavailable or loading, the Translation Status page uses new Date().toISOString(). That means that the visual regression snapshot for the loading state of the page will constantly have a different date on it.

While we could probably mock Date() to make that less flaky for the visual regression tests, I think it would be more correct for the page to show something else like loading or unavailable when the data isn't present.

Originally posted by @cylewaitforit in #2559 (comment)

Additional context

No response

Logs

[cylewaitforit]

Closed by #2589