This PR does a few things to make the process of setting up an app on
Heroku better and cheaper.

1. It adds a buildpack for `jemalloc` and sets the `JEMALLOC_ENABLED`
   ENV var. Fixes: bullet-train-co/bullet_train#1524
2. Makes the initial setup cheaper by using smaller dynos and the entry
   level for a number of addons. Fixes: bullet-train-co/bullet_train#1127
3. Removes the Sentry addon. This was redundant since Honeybadger was
   already included, and Sentry isn't supported in review apps on
   Heroku, so having it in `app.json` prevents the use of review apps
   entirely which is frustrating. Fixes: bullet-train-co/bullet_train#1521
4. Sets `RAILS_MAX_THREADS` and `WEB_CONCURRENCY` to match the values
   suggested by heroku here: https://devcenter.heroku.com/articles/deploying-rails-applications-with-the-puma-web-server#recommended-default-puma-process-and-thread-configuration
   Fixes: bullet-train-co/bullet_train#1523

Co-authored-by: jagthedrummer <[email protected]>

* Run the PartialTest on a dedicated CI node

Previously every node that ran _any_ super scaffolding test would also run
the super scaffolding test for `PartialTest`.

This PR makes it so that we run that test on a dedicated node, and all
the other nodes won't run it.

* Need to keep that

* consolidate some tests onto the same CI node

Co-authored-by: jagthedrummer <[email protected]>

Co-authored-by: jagthedrummer <[email protected]>

* Bump setup-node to v4

* Update actions/cache to v4

Some users are reporting crashes on MacOS when first trying to access
the database. There's an issue open on `ruby-pg` that describes this
temporary workaround. ged/ruby-pg#538

Hopefully fixes: bullet-train-co/bullet_train#1379

* wip

* making progress

* more refactoring

* tweak

* Move some stuff out of bin/configure and into bin/setup

* linter

Co-authored-by: depfu[bot] <23717796+depfu[bot]@users.noreply.github.com>

Co-authored-by: jagthedrummer <[email protected]>

# Conflicts:
#	Gemfile.lock