Allow experiment classed to not be namespaced

This is because all experiments are so far circumventing the rule, as
well as they may span an area of focus. The experiment feature flags
can be useful for this, or we can choose to solve this challenge in a
different and more nuanced way.

.rubocop.yml

@@ -666,6 +666,7 @@ Gitlab/NamespacedClass:
     - 'ee/elastic/**/*.rb'
     - 'scripts/**/*'
     - 'spec/migrations/**/*.rb'
+    - 'app/experiments/**/*_experiment.rb'
 
 Lint/HashCompareByIdentity:
   Enabled: true

app/experiments/application_experiment.rb

 # frozen_string_literal: true
 
-class ApplicationExperiment < Gitlab::Experiment # rubocop:disable Gitlab/NamespacedClass
+class ApplicationExperiment < Gitlab::Experiment
   def publish(_result = nil)
     super
 

app/experiments/combined_registration_experiment.rb

 # frozen_string_literal: true
 
-class CombinedRegistrationExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class CombinedRegistrationExperiment < ApplicationExperiment
   include Rails.application.routes.url_helpers
 
   def key_for(source, _ = nil)

app/experiments/empty_repo_upload_experiment.rb

 # frozen_string_literal: true
 
-class EmptyRepoUploadExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class EmptyRepoUploadExperiment < ApplicationExperiment
   include ProjectCommitCount
 
   TRACKING_START_DATE = DateTime.parse('2021/4/20')

app/experiments/force_company_trial_experiment.rb

 # frozen_string_literal: true
 
-class ForceCompanyTrialExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class ForceCompanyTrialExperiment < ApplicationExperiment
   exclude :setup_for_personal
 
   private

app/experiments/in_product_guidance_environments_webide_experiment.rb

 # frozen_string_literal: true
 
-class InProductGuidanceEnvironmentsWebideExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class InProductGuidanceEnvironmentsWebideExperiment < ApplicationExperiment
   exclude :has_environments?
 
   def control_behavior

app/experiments/new_project_sast_enabled_experiment.rb

 # frozen_string_literal: true
 
-class NewProjectSastEnabledExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class NewProjectSastEnabledExperiment < ApplicationExperiment
   def publish(_result = nil)
     super
 

app/experiments/require_verification_for_namespace_creation_experiment.rb

 # frozen_string_literal: true
 
-class RequireVerificationForNamespaceCreationExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class RequireVerificationForNamespaceCreationExperiment < ApplicationExperiment
   exclude :existing_user
 
   EXPERIMENT_START_DATE = Date.new(2022, 1, 31)

app/experiments/security_reports_mr_widget_prompt_experiment.rb

 # frozen_string_literal: true
 
-class SecurityReportsMrWidgetPromptExperiment < ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
+class SecurityReportsMrWidgetPromptExperiment < ApplicationExperiment
   def publish(_result = nil)
     super