feat(test): attachments removal plugin

[saturninoabril]

Summary

• Added new test cases for Attachments Removal plugin - https://github.com/mattermost/mattermost-plugin-attachments-remover

Other:

• Added Deployment Eng to team owners custom fields
• Cleaned up unused team owner

Is the feature in stable branch or under review?

• [] Feature in stable branch (master, main)?
• Feature still under review? If yes, list all related pull requests for reference.

Test client

• Browser
• [] Mobile App (version, OS)
• Desktop App

[saturninoabril]

Merging this now so we can save the test cases in our test management and will be able to create test cycle, but please continue to review and we'll update the test cases accordingly.