Remove COUNT from logging sources/views

[frankmcsherry]

Many of the logging sources and views have a COUNT, associating a number with various other attributes. For example, we track the elapsed number of nanoseconds for each operator, the counts for each power-of-two elapsed scheduling event, counts of number of records and batches in arrangements.

We could not do that, and just leave the uncounted data as the collection.

The benefit here is that the count adds additional work, additional state, and additional churn when data change. If the user wants to count the results they can, and instead if the user wants to project out certain columns (often: worker) they wouldn't have to write the SUM to perform the accumulation.

There are several things we do badly at the moment that might prevent this from working well yet, mostly about how well we could use raw arrangements in places where we currently use arrangements with a value (e.g. a count).

[antiguru]

All but some materialized logs do not explicitly count anymore. I'll go ahead and close this issue because I don't expect the remaining logs to have a large volume.