[web] fix icons sizes in community picker side bar

Summary:
adjust icon sizes to now that we have included padding in the icon sets

https://www.figma.com/file/a1nkbWgbgjRlrOY9LVurTz/?node-id=1170%3A77104

Test Plan: check figma that the icons are now the correct size

Reviewers: atul, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3325