MM-62558 Add E2E tests for custom profile settings (#30722)

* add e2e tests for custom profile settings

* fix failed tests

* reorg folder and file convention, and add more details of the tests

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Co-authored-by: Mattermost Build <build@mattermost.com>

e2e-tests/playwright/specs/accessibility/channels/intro_channel.spec.ts

@@ -37,7 +37,7 @@ test('Post actions tab support', async ({pw, axe}) => {
     await channelsPage.toBeVisible();
     await channelsPage.centerView.postCreate.postMessage('hello');
 
-    const post = await channelsPage.centerView.getLastPost();
+    const post = await channelsPage.getLastPost();
     await post.hover();
     await post.postMenu.toBeVisible();