Avoid initializing geocoder in test environments

[aduth]

🛠 Summary of changes

Updates geocoder initializer to avoid loading the geocoder file in test environments.

This is a partial reversal of #10319, while still allowing the geocoder to be initialized for local development.

This resolves an issue where tests may fail when trying to geocode an IP address.

📜 Testing Plan

1. Follow the instructions to set up geolocation
   1. Alternatively, download live database from S3
2. Run: rspec spec/controllers/users/piv_cac_login_controller_spec.rb
3. Observe all tests pass

Previous failure example:

      Failure/Error: @geocoded_location ||= Geocoder.search(ip).first
      
      ActionView::Template::Error:
        unknown stub request 0.0.0.0
      # ./app/services/ip_geocoder.rb:42:in `geocoded_location'