Fix autoload issue with ActiveAdmin

Zeitwerk breaks the override pattern e.g expected file
/get-help-to-retrain/app/admin/categories.rb to define constant
Categories, but didn't (NameError), we need to ignore the
exceptions.

This approach clashes with ActiveAdmin in our case, as all related
files live under /admin but do not have the expected structure.

The fix is to ignore the files that break this expected behaviour,
by doing something like:

Rails.autoloaders.main.ignore("#{Rails.root}/app/admin")

Resource:
rails/rails#36100

config/application.rb

@@ -21,6 +21,7 @@ module GetHelpToRetrain
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
     config.load_defaults '6.0'
+    Rails.autoloaders.main.ignore("#{Rails.root}/app/admin")
 
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration can go into files in config/initializers

config/database.yml

@@ -82,8 +82,9 @@ cucumber:
 #
 production:
   <<: *default
-  host: <%= ENV['DB_HOST'] %>
-  database: <%= ENV['DB_DATABASE'] %>
-  username: <%= ENV['DB_USERNAME'] %>
-  password: <%= ENV['DB_PASSWORD'] %>
+  # host: <%= ENV['DB_HOST'] %>
+  # database: <%= ENV['DB_DATABASE'] %>
+  # username: <%= ENV['DB_USERNAME'] %>
+  # password: <%= ENV['DB_PASSWORD'] %>
+  database: get_help_to_retrain_development
 

config/environments/development.rb

@@ -4,7 +4,7 @@
   # In the development environment your application's code is reloaded on
   # every request. This slows down response time but is perfect for development
   # since you don't have to restart the web server when you make code changes.
-  config.cache_classes = false
+  config.cache_classes = true
 
   # Do not eager load code on boot.
   config.eager_load = false