Since now generating stats (assuming the results aren't in the cache)
only takes a few seconds even when there are a hundred thousand
participants, as opposed to the several minutes it took to generate them
when we introduced the Cron job, we can simply generate the stats during
the first request to the stats page.
Note that, in order to avoid creating a temporary table when the stats
are cached, we're making sure we only create this table when we need to.
Otherwise, we could spend up to 1 second on every request to the stats
page creating a table that isn't going to be used.
Also note we're using an instance variable to check whether we're
creating a table; I tried to use `table_exists?`, but it didn't work. I
wonder whether `table_exists?` doesn't detect temporary tables.
We were very inconsistent regarding these rules.
Personally I prefer no empty lines around blocks, clases, etc... as
recommended by the Ruby style guide [1], and they're the default values
in rubocop, so those are the settings I'm applying.
The exception is the `private` access modifier, since we were leaving
empty lines around it most of the time. That's the default rubocop rule
as well. Personally I don't have a strong preference about this one.
[1] https://rubystyle.guide/#empty-lines-around-bodies
It will make it far easier to call other methods on the stats object,
and we're already caching the methods.
We had to remove the view fragment caching because the stats object
isn't as easy to cache. The good thing about it is the view will
automatically be updated when we change logic regarding which stats to
show, and the methods taking long to execute are cached in the model.
Note that we are relying on the existing `sort_by_name`[1] method in the `Budget::Heading` class.
This method sorts by DESC group name first and then ASC heading name.
[1] https://github.com/AyuntamientoMadrid/consul/pull/1875
