Apply active class on link element in HAML pagination

What does this MR do?

This applies the .active class on the active <a> tag in HAML/Kaminari pagination to ensure that it inherits GitLab UI's CSS rules.

The Kaminari pagination is used in the issues page among others: https://gitlab.com/gitlab-org/gitlab/-/issues

Screenshots

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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

Closes #213392 (closed)