Roster: Don't build resources submenu for start_chat_menuitem

This avoids being able to open multiple ChatControls for one contact.
Historically, this was used to send a message to a specific resource.
3 jobs for start-chat-resources in 3 minutes and 3 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #14287
run-appdata

00:00:08

passed #14286
run-tests

00:02:39

 
  Build
passed #14288
run-build

00:00:15