Remove `promo_` implicit licensed feature flags

It appears that we did never use this feature.
To reduce amount of feature flags we should remove
it and add it if this is deems to be needed.

doc/development/licensed_feature_availability.md

@@ -35,7 +35,3 @@ the instance license.
 ```ruby
 License.feature_available?(:feature_symbol)
 ```
-
-## Enabling promo features on GitLab.com
-
-A paid feature can be made available to everyone on GitLab.com by enabling the feature flag `"promo_#{feature}"`.

ee/app/models/ee/namespace.rb

@@ -148,8 +148,6 @@ module EE
     end
 
     def feature_available_in_plan?(feature)
-      return true if ::License.promo_feature_available?(feature)
-
       available_features = strong_memoize(:features_available_in_plan) do
         Hash.new do |h, f|
           h[f] = (plans.map(&:name) & self.class.plans_with_feature(f)).any?

ee/app/models/license.rb

@@ -298,10 +298,6 @@ class License < ApplicationRecord
       Gitlab::CurrentSettings.license_trial_ends_on
     end
 
-    def promo_feature_available?(feature)
-      ::Feature.enabled?("promo_#{feature}", default_enabled: false)
-    end
-
     def history
       all.sort_by { |license| [license.starts_at, license.created_at, license.expires_at] }.reverse
     end

ee/spec/models/ee/namespace_spec.rb

@@ -368,25 +368,6 @@ RSpec.describe Namespace do
       end
     end
 
-    context 'when the feature is temporarily available on the entire instance' do
-      let(:feature) { :ci_cd_projects }
-
-      before do
-        stub_application_setting_on_object(group, should_check_namespace_plan: true)
-        stub_feature_flags(promo_ci_cd_projects: true)
-      end
-
-      it 'returns true when the feature is available globally' do
-        stub_licensed_features(feature => true)
-
-        is_expected.to be_truthy
-      end
-
-      it 'returns `false` when the feature is not included in the global license' do
-        is_expected.to be_falsy
-      end
-    end
-
     context 'when feature is disabled by a feature flag' do
       it 'returns false' do
         stub_feature_flags(feature => false)

ee/spec/models/license_spec.rb

@@ -850,26 +850,6 @@ RSpec.describe License do
     end
   end
 
-  describe '#promo_feature_available?' do
-    subject { described_class.promo_feature_available?(:container_scanning) }
-
-    context 'with promo_container_scanning disabled' do
-      before do
-        stub_feature_flags(promo_container_scanning: false)
-      end
-
-      it { is_expected.to be_falsey }
-    end
-
-    context 'with promo_container_scanning enabled' do
-      before do
-        stub_feature_flags(promo_container_scanning: true)
-      end
-
-      it { is_expected.to be_truthy }
-    end
-  end
-
   describe '.history' do
     before(:all) do
       described_class.delete_all

ee/spec/models/project_spec.rb

@@ -809,17 +809,6 @@ RSpec.describe Project do
                   is_expected.to eq(false)
                 end
               end
-
-              context 'with promo feature flag' do
-                let(:allowed_on_global_license) { true }
-
-                before do
-                  project.clear_memoization(:licensed_feature_available)
-                  stub_feature_flags("promo_#{feature}" => true)
-                end
-
-                it { is_expected.to be_truthy }
-              end
             end
           end
 

spec/support/helpers/stubbed_feature.rb

@@ -37,10 +37,7 @@ module StubbedFeature
       # We do `m.call` as we want to validate the execution of method arguments
       # and a feature flag state if it is not persisted
       unless Feature.persisted_name?(args.first)
-        # TODO: this is hack to support `promo_feature_available?`
-        # We enable all feature flags by default unless they are `promo_`
-        # Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/218667
-        feature_flag = true unless args.first.to_s.start_with?('promo_')
+        feature_flag = true
       end
 
       feature_flag