Use standard Airbrake configuration
Use standard Airbrake configuration

This is the default GOV.UK Airbrake config now, which reads from ENV
instead of relying on overwriting files. It's taken from

https://github.com/alphagov/govuk-rails-app-template

It's safe to deploy because until the corresponding change has been
made in alphagov-deployment, this file still gets overwritten.

alphagov/finder-frontend,alphagov/finder-frontend,alphagov/finder-frontend,alphagov/finder-frontend