Remove deterministic download schedule code and configs
Under exponential backoff, download schedules contain the
maximum time we will wait, even if the random amount is larger. initial time we will wait, and everything else is random exponential from that point onwards. But in most cases, the random amount is much smaller than the maximum, so we could replace the item with the actual maximum, or delete it from the schedule altogether. (On the public network, the maximum is 4x the last entry, on test networks, it's 3x.)
So once we're sure that we will never revert to deterministic schedules, we should make each schedule into a single initial value, and remove the deterministic code.
We should make these changes based on the schedules in legacy/trac#23347 (moved).