Comment 0 for bug 2018695

[Impact]

Ubuntu Studio introduced a way to switch between the new PipeWire-based audio configuration and the older JACK/PulseAudio-based audio configuration in the 23.04 release cycle. This was not without complications throughout the entire process as PulseAudio had become so deeply embedded that even the germinate seed had some assumptions that PulseAudio would never go away.

As such, in order to prevent PulseAudio dependencies from automatically installing where equivalent PipeWire alternatives exist via `pipewire-pulse`, `pipewire-pulse` had to be seeded as a pre-seed for the `ubuntustudio-audio` and `ubuntustudio-video` seeds in order to prevent image build failures.

However, since pipewire-pulse was seeded as a hard dependency and not as a recommends, when one went to switch to the pulseaudio configuration via the `ubuntstudio-pulseaudio-config` package, it would uninstall the ubuntustudio-audio and ubuntustudio-video metapackages. Upon attempting to reinstall those metapackages, it would reinstall pipewire-pulse, which would break the ubuntustudio-pulseaudio-config package.

A fix is to this would be as simple as demoting the pre-seed of pipewire-pulse to recommends.

[Test Case]

 * Install Ubuntu Studio 23.04

 * Install ubutustudio-pulseaudio-config
   - Notice ubuntustudio-audio and ubuntustudio-video would be REMOVED. This is not desired.

 * Further testing can continue from here, but removal of those two metapackages is proof enough of the breakage.

[Regression Potential]

The biggest regression potential in this would be that seeds in Mantic would have trouble building as a result of this change. I don't see this as happening as the entire point is to simply get it in before pulseaudio, and that happens regardless of depends or recommends.