Migrated Read more button to Pajamas on project env page

What does this MR do and why?

Implements #395779 (closed) which migrates the Read more button on the Project Environments page to use a Pajamas button component.

There should be no visible change.

Screenshots or screen recordings

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Navigate to Project > Environments
2. Create an Env or click on an existing one
3. Check the Read more button

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #395779 (closed)