Restyle license compliance buttons

What does this MR do?

This MR solves #229910 (closed).

It restyles the license compliance Buttons in the Merge Request Widget to stay consistent with the styles on the Security Scanning MR Widget.

How to reproduce:

1. create a MR in a repo where License Compliance and Security Scanning are enabled
2. find the widget on the Merge Request Page

Screenshots (strongly suggested)

before	after	after (with collapsible report)

Demo Video

license-buttons

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• [-] 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