Update ServicesUpdate.removed and ServicesUpdate.created to use Maps instead of Arrays

[skoszuta]

For faster lookups, such as in the .find() in #754

[tomusdrw]

FYI: https://jsperf.app/pisogo/2 we might want to create something like NumericMap<K extends number, V> which is backed by a plain object, since it's much, much faster (3x) than Map and faster than Array even for couple of elements.