Patch pipewire-pulse.service to be sure it is started after a session manager

The beginning of the discussion: wireplumber!10 (closed)

@biebl Thanks for your help! This MR fixes the missing part of the alias deletion in wireplumber and pipewire-media-session.

And because wireplumber and pipewire-media-session packages are in conflict, systems have only wireplumber.service or pipewire-media-session.service. Isn't it a problem to have missing services in After or Wants. Based on the systemd documentation, it seems it is okay for Wants but not sure for After. At least it works during my test.

CC @jbicha We also need this for Ubuntu 22.10.