When a RepeatType.Relative scheduled task has to do time travel catch-up, its relative interval changes

[Ixrec]

This is probably because Relative tasks don't actually store their interval, only LastExecutedAt and ExecuteAt. So e.g. if a daily task is LastExecutedAt Jan 1st, and the bot is down for Jan 2nd through 10th, then when the bot comes back on Jan 11th it immediately executes, setting the task to LastExecutedAt Jan 11th and ExecuteAt Jan 21st. The bug is that ExecuteAt: it's become a 10 day task instead of a daily task.

When I noticed this I manually fixed it for the tasks that appeared to be affected. This issue is for preventing future recurrences, presumably by actually storing an interval like we should've done to begin with.