[dev-v5][MessageBar] Remove not working CSS rule

[MarvinKlein1508]

Pull Request

📖 Description

This removes a small potion of CSS from FluentMessageBar which is not working. it was supposed to grow the message .content from the hardcoded 520px to max block size but this rule will always be ignored. So I removed it to shrink down the file size a bit.

✅ Checklist

General

• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• I have added a new component
• I have added Unit Tests for my new component
• I have modified an existing component
• I have validated the Unit Tests for an existing component

⏭ Next Steps

[dvoituron]

The purpose of this code was to prevent this outcome, namely that a max-width: 520px property be included in the web component.

The problem is that the web component hasn't defined the “content” section with a part=“content” attribute. Therefore, it's not possible to apply CSS styles to it.

Two solutions:

1. Submit a request or a PR to the web component's fluentui repository
2. Write some JavaScript to apply this change programmatically: $0.shadowRoot.querySelector('.content').style.maxWidth = 'unset'

Can you do that?