Stop compiling assets outside production

If we use `bin/rails spec` to run our specs in CI we will not need to
compile the assets - this should save some time building the image for
CI.

The reason is that the `spec` task includes `test:prepare` which builds
the assets in test.

.github/workflows/ci_checks.yml

@@ -54,7 +54,7 @@ jobs:
         name: Run Rspec and Simplebcov
         run: |
           docker compose -p app_test -f docker-compose.ci.yml \
-            run --name app_test test /bin/bash -c "bin/rspec --format=documentation"
+            run --name app_test test /bin/bash -c "bin/rails spec"
       -
         name: Shutdown containers
         run: docker compose -p app_test down && docker compose -p app_test rm

.rspec

@@ -1,2 +1,3 @@
 --require spec_helper
 --require rails_helper
+--format documetnation

Dockerfile

@@ -115,13 +115,9 @@ COPY . ${APP_HOME}
 RUN cp -R $DEPS_HOME/node_modules $APP_HOME/node_modules
 RUN cp -R $DEPS_HOME/node_modules/govuk-frontend/govuk/assets $APP_HOME/app/assets
 
-RUN \
-  RAILS_ENV=$RAILS_ENV \
-  DOMAIN="stand-in.local" \
-  SECRET_KEY_BASE="super secret" \
-  DATABASE_URL="postgres://stand-in:5432" \
-  REDIS_URL="redis://stand-in.local:6379" \
-  bundle exec rake assets:precompile --quiet
+RUN if [ ${RAILS_ENV} = "production" ]; then \
+  bundle exec rake assets:precompile --quiet; \
+  fi
 
 # create tmp/pids
 RUN mkdir -p tmp/pids