housekeeping: Remove usage of `Time.AddDate(...)`

Currently we use Time.AddDate(...) in a few places in the housekeeping package. The problem with this is that it directly adds/subtracts days from the current time. This would not work well with DST changes. For e.g. if you're subtracting day around the time of when DST changes happen, you could potentially gain/loose an hour.

Instead lets use Time.Add(...) where we'd specify the number of hours to be added/subtracted.