[web] [refactor] move hasUsername logic to variable

Summary:
move logic to variable thats descriptive of what it checks for

Test Plan: no new added functionality, username should render as normal

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

Reviewed By: ashoat

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

Differential Revision: https://phabricator.ashoat.com/D3508