Remove Runner#belonging_to_any_project since this is no longer needed

app/controllers/projects/settings/ci_cd_controller.rb

@@ -72,7 +72,6 @@ module Projects
           .ci_authorized_runners
           .assignable_for(project)
           .ordered
-          .belonging_to_any_project
           .page(params[:page]).per(20)
 
         @shared_runners = ::Ci::Runner.shared.active

app/models/ci/runner.rb

@@ -32,8 +32,6 @@ module Ci
       joins(:runner_projects).where(ci_runner_projects: { project_id: project_id })
     }
 
-    scope :belonging_to_any_project, -> { joins(:runner_projects) }
-
     scope :belonging_to_parent_group_of_project, -> (project_id) {
       project_groups = ::Group.joins(:projects).where(projects: { id: project_id })
       hierarchy_groups = Gitlab::GroupHierarchy.new(project_groups).base_and_ancestors

spec/models/ci/runner_spec.rb

@@ -137,21 +137,6 @@ describe Ci::Runner do
     end
   end
 
-  describe '.belonging_to_any_project' do
-    it 'returns the specific project runner' do
-      # project
-      project_project = create(:project)
-      project_runner = create(:ci_runner, :specific, projects: [project_project])
-
-      # group
-      group = create(:group)
-      create(:project, group: group)
-      create(:ci_runner, :specific, groups: [group])
-
-      expect(described_class.belonging_to_any_project).to eq [project_runner]
-    end
-  end
-
   describe '.belonging_to_parent_group_of_project' do
     let(:project) { create(:project, group: group) }
     let(:group) { create(:group) }