Fix is_groupchat call

is_groupchat is now a property

Fixes #9742
3 jobs for master in 2 minutes and 47 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #11830
run-appdata

00:00:05

passed #11829
run-tests

00:02:31

 
  Build
passed #11831
run-build

00:00:09