Consider adding a banner that gives information about missing data

[fbertsch]

We have now deleted a substantial amount of data, and queries may look strange for awhile. Since re:dash doesn't support annotations, we should consider a small banner at the top that indicates the dates of the outage, and points to the bug with details about deletion. Bonus points for pointing to a list of affected datasets directly.

[jezdez]

@fbertsch Is this still relevant?

[fbertsch]

Nope, I would say it's not any longer, it's been long enough and most queries aren't hitting that data anymore.