[landing] redesign servers section on keyserver page

Summary:
This diff updates the UI for the middle section of the keyserver page to match the figma designs. Subsequent diffs will address the first section. Here is the design for reference:

Depends on D8165

Test Plan:
Please view the demo video/screenshot:

Desktop/Responsive:

Tablet:

Mobile:

Reviewers: atul, kamil

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8166