test: fix JsObjectMutation flaky test (#32936)

RCA:


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit


- **Tests**
- Updated the test specification file and focused test execution on a
specific test case.
- Added a new assertion to verify the presence of a specific element in
the DOM.
- Added a new declaration to the `CommonLocators` class for improved
test reliability.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

app/client/cypress/e2e/Regression/ClientSide/JSObject/JSObjectMutation_spec.ts

@@ -1,8 +1,10 @@
 import { getWidgetSelector } from "../../../../locators/WidgetLocators";
+import { locators } from "../../../../support/Objects/ObjectsCore";
 import * as _ from "../../../../support/Objects/ObjectsCore";
 import EditorNavigation, {
  EntityType,
 } from "../../../../support/Pages/EditorNavigation";
+const commonlocators = require("../../../../locators/commonlocators.json");
 
 describe("JSObject testing", { tags: ["@tag.JS"] }, () => {
  before(() => {
@@ -128,6 +130,7 @@ describe("JSObject testing", { tags: ["@tag.JS"] }, () => {
  toRun: false,
  shouldCreateNewJSObj: true,
  });
+ _.agHelper.GetNAssertContains(locators._selectionItem, "getData");
  _.jsEditor.SelectFunctionDropdown("myFun1");
  _.jsEditor.RunJSObj();
  EditorNavigation.SelectEntityByName("Text2", EntityType.Widget);

app/client/cypress/support/Objects/CommonLocators.ts

@@ -329,4 +329,5 @@ export class CommonLocators {
  _exitFullScreen = ".application-demo-new-dashboard-control-exit-fullscreen";
  _menuItem = ".bp3-menu-item";
  _slashCommandHintText = ".slash-command-hint-text";
+ _selectionItem = ".rc-select-selection-item";
 }