conversation-list: construct string in place for single participant

Signed-off-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
5 jobs for <span class="ref-name">emphasize-participated-in</span> in 23 minutes and 53 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #279235
fedora

00:09:26

passed #279236
ubuntu

00:10:29

 
  Test
passed #279237
flatpak

00:12:54

 
  Deploy
passed #279238
review

00:00:29

manual #279239
allowed to fail manual
stop_review