Add downtime recording rules for moving time windows

[istvanballok]

What this PR does / why we need it:

Add downtime recording rules for moving time windows

[wyb1]

One open question is if we should do 4 weeks or 30 days for the moving window "month". 4 weeks is nice because it builds on the previous recording rule, but 30 days is usually closer to the length of a month.

[istvanballok]

I think I chose 4 weeks because I remember reading something about it in the SRE book. I looked it up now:

https://sre.google/workbook/implementing-slos/

We recommend defining this period as an integral number of weeks so it always contains the same number of weekends. For example, if you use a 30-day window, some periods might include four weekends while others include five weekends. If weekend traffic differs significantly from weekday traffic, your SLIs may vary for uninteresting reasons.