Remove username from invite page

Will be shown in header, so not needed on page as well

Issue: GREG-75

frontend/src/routes/invite/index.tsx

 import { useTranslation } from 'react-i18next'
 import Page from 'components/page'
-import { useUserContext } from 'contexts'
 
 import { styled } from '@mui/material/styles'
 
@@ -13,14 +12,12 @@ const FlexDiv = styled('div')(() => ({
 }))
 
 function Invite() {
-  const { user } = useUserContext()
   const { t } = useTranslation(['invite'])
 
   return (
     <Page>
       <h1>{t('header')}</h1>
       <p>
-        {user.first_name} {user.last_name}
         {t('description')}
       </p>
       <FlexDiv>