Mattermost-server: UI Automation: Write an automated test using Cypress for "Remove last post in channel"

[saturninoabril]

Test Key: M18716
Test folder: /cypress/integration/messaging
Title: Remove last post in channel

Steps:
1) View an empty channel (such as a DM channel with a user you've never messaged)
2) Make a post
3) Delete that post

Expected:
The channel is still displayed

See our end-to-end testing documentation for reference.

Jira ticket: MM-18716

---

If you're interested, please comment here and come join our "Contributors" community channel on our daily build server, where you can discuss questions with community members and the Mattermost core team. For technical advice or questions, please join our "Developers" community channel.

New contributors please see our Developer's Guide.

[josephk96]

I submitted a PR :)

[hanzei]

Thanks @josephk96

[saturninoabril]

Thanks Joseph for your contribution1