Reduce number of pipelines created to test pagination

stub pagination in tests

app/assets/javascripts/vue_pipelines_index/pipelines.js.es6

@@ -56,7 +56,7 @@ const CommitPipelinesStoreWithTimeAgo = require('../commit/pipelines/pipelines_s
        */
       change(pagenum, apiScope) {
         if (!apiScope) apiScope = 'all';
-        gl.utils.visitUrl(`?scope=${apiScope}&p=${pagenum}`);
+        gl.utils.visitUrl(`?scope=${apiScope}&page=${pagenum}`);
       },
     },
     template: `

spec/features/projects/pipelines/pipelines_spec.rb

@@ -288,23 +288,22 @@ describe 'Pipelines', :feature, :js do
 
       context 'with pagination' do
         before do
-          create_list(:ci_empty_pipeline, 40, project: project)
+          allow(Ci::Pipeline).to receive(:default_per_page).and_return(1)
+          create(:ci_empty_pipeline,  project: project)
         end
 
         it 'should render pagination' do
           visit namespace_project_pipelines_path(project.namespace, project)
           wait_for_vue_resource
 
-          expect(page).to have_css('.gl-pagination')
-          expect(page.find_all('tbody tr').length).to eq(20)
+          expect(page).to have_selector('.gl-pagination')
         end
 
-        it "should render second page of pipelines" do
+        it 'should render second page of pipelines' do
           visit namespace_project_pipelines_path(project.namespace, project, page: '2')
           wait_for_vue_resource
 
-          expect(page).to have_css('.gl-pagination')
-          expect(page.find_all('tbody tr').length).to eq(20)
+          expect(page).to have_selector('.gl-pagination .page', count: 2)
         end
       end
     end