Migrate MM-53377 regression test from Cypress to Playwright (#29460)

* feat: Migrate MM-53377 regression test from Cypress to Playwright

* fix: Update mm_53377 regression test to use admin client for setup

* fix: Correct admin client usage in mm_53377 regression test

* refactor: Standardize mm_53377 Playwright test with consistent naming and imports

* fix: Mark MM-T53377 test as fixme for investigation

* Migrating mm_53377_regression_test_spec.js cypress test to playwright

* Fixing linter errors

* Addressing PR review comment

* Fixing broken test

e2e-tests/playwright/support/ui/components/channels/post_create.ts

@@ -11,6 +11,7 @@ export default class ChannelsPostCreate {
     readonly emojiButton;
     readonly sendMessageButton;
     readonly scheduleDraftMessageButton;
+    readonly suggestionList;
 
     constructor(container: Locator, isRHS = false) {
         this.container = container;
@@ -25,6 +26,7 @@ export default class ChannelsPostCreate {
         this.emojiButton = container.getByLabel('select an emoji');
         this.sendMessageButton = container.getByTestId('SendMessageButton');
         this.scheduleDraftMessageButton = container.getByLabel('Schedule message');
+        this.suggestionList = container.getByTestId('suggestionList');
     }
 
     async toBeVisible() {

e2e-tests/playwright/support/ui/components/channels/user_profile_popover.ts

@@ -0,0 +1,22 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+import {expect, Locator} from '@playwright/test';
+
+export default class UserProfilePopover {
+    readonly container: Locator;
+
+    constructor(container: Locator) {
+        this.container = container;
+    }
+
+    async toBeVisible() {
+        await expect(this.container).toBeVisible();
+    }
+
+    async close() {
+        await this.container.getByLabel('Close user profile popover').click();
+    }
+}
+
+export {UserProfilePopover};