Replace max width 90% from job dropdown with a min-width of 0

What does this MR do?

To ensure that the text was cut off properly in the job dropdown component, there was a max-width of 90% which was working properly, but was a bit more flaky than this solution based on having the flex items have a min-width of 0. We also remove unused classes. One example of a blog with more information: https://makandracards.com/makandra/66994-css-flex-and-min-width

This shouldn't change anything visually and simply be a more long term solution. No changelog required as the change is not user facing.

Screenshots (strongly suggested)

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team