Fix states and add border radius on the filter search

What does this MR do?

• Applies the correct hover and focus states to the Recent Searches button.
• Applies the correct border radius to the Recent Searches button and the search input field

Screenshots

Recent Searches Button Hover Before	Recent Searches Button Hover Before

Recent Searches Button Focus Before	Recent Searches Button Focus 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

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

Closes #28965 (closed)