Verify in CI that fast unit specs load without errors

Follow-up of https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78543

.gitlab/ci/rails.gitlab-ci.yml

@@ -335,7 +335,9 @@ rspec fast_spec_helper:
     - .rspec-base-pg12
     - .rails:rules:ee-and-foss-fast_spec_helper
   script:
-    - bin/rspec spec/fast_spec_helper.rb
+    - fast_spec_helper_specs=$(git grep -l -E '^require.*fast_spec_helper')
+    # Load fast_spec_helper as well just in case there are no specs available.
+    - bin/rspec --dry-run spec/fast_spec_helper.rb $fast_spec_helper_specs
 
 rspec fast_spec_helper minimal:
   extends:

spec/lib/gitlab/endpoint_attributes_spec.rb

 # frozen_string_literal: true
 
 require 'fast_spec_helper'
-require_relative "../../support/matchers/be_request_urgency"
-require_relative "../../../lib/gitlab/endpoint_attributes"
+require_relative '../../support/matchers/be_request_urgency'
+require_relative '../../../lib/gitlab/endpoint_attributes/config'
+require_relative '../../../lib/gitlab/endpoint_attributes'
 
 RSpec.describe Gitlab::EndpointAttributes do
   let(:base_controller) do