tests: add pipewire env variables when running tests, tidy up common_env

Related to pipewire!767
2 jobs for pwenv in 1 minute and 51 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Container
passed container_fedora #11041515

00:00:45

 
  Build
passed build_on_fedora #11041516

00:01:06