refactor(messenger-main): remove outdated rendering, processing and social channel handling of MessengerFeed from main messenger container

[domw30]

What does this do?

• We're removing the MessengerFeed component import and social channel conditional rendering from the Main container.

Why are we making this change?

• The Main container was still importing MessengerFeed and checking for social channels despite this functionality being moved to a separate app. This outdated code adds unnecessary complexity, performs redundant state derivation via denormalize, and potentially impacts performance by running unnecessary checks on each render.

How do I test this?

• run tests as usual

Key decisions and Risk Assessment:

Things to consider:

1. How will this affect security?
2. How will this affect performance?
3. Does this change any APIs?