Change default value for isMergeTrain prop

app/assets/javascripts/pipelines/components/pipelines_list/stage.vue

@@ -41,7 +41,7 @@ export default {
     isMergeTrain: {
       type: Boolean,
       required: false,
-      default: true,
+      default: false,
     },
   },
   data() {

spec/frontend/pipelines/stage_spec.js

@@ -195,9 +195,7 @@ describe('Pipelines stage component', () => {
   describe('With merge trains disabled', () => {
     beforeEach(async () => {
       mock.onGet(dropdownPath).reply(200, stageReply);
-      createComponent({
-        isMergeTrain: false,
-      });
+      createComponent();
 
       await openStageDropdown();
       await axios.waitForAll();