refactor: Utilize semantic font family LESS vars

[lokesh]

Issue # https://github.com/internetarchive/openlibrary/issues/11555

This PR is a follow-up to, and should be merged after: refactor: Define semantic font family LESS vars #11540

Technical

Utilizes new semantic font-family variables across codebase.

This creates one place in the codebase to manage font-families on site: static/css/less/font-families.less

Testing

Screenshot

Stakeholders

@cdrini @mekarpeles @jimchamp

^ Let me know if this set of stakeholders is appropriate or anything else I can do to make triaging easier.