[keyserver] [chore] [ENG-1025] remove old landing images

Summary: remove svg's that are no longer in use on landing. The images are now hosted on aws. https://linear.app/comm/issue/ENG-1025/remove-old-images-from-keyserver-for-landing-page

Test Plan: run landing. All images still load as expected.

Reviewers: atul, palys-swm, def-au1t, yayabosh

Reviewed By: atul

Subscribers: ashoat, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3791