Replace references to `master` with `primary`

See #324
5 jobs for wip/324-remove-master-slave in 29 minutes and 26 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #260953
fedora

00:03:47

passed #260954
ubuntu

00:13:28

 
  Test
passed #260955
flatpak

00:14:45

 
  Deploy
passed #260956
review

00:00:25

passed #260957
allowed to fail manual
stop_review

00:00:45