[client] pipewire: Stop loading properties from client-rt.conf

[netboy3]

Pipewire now automatically moves non-rt clients into non-rt threads so client-rt.conf is obsolete. Pipewire will now emit a deprecation warning if a client tries to load RT config properties which LG does. Stop loading RT properties during context initialization for Pipewire 1.3.81 and newer. See: https://gitlab.freedesktop.org/pipewire/pipewire/-/commit/24bcacc6195ffbf8e40c9ea1374eb6666252eadc

[spencercw]

More importantly, PipeWire now applies realtime priority automatically under the default configuration, provided the user has appropriate permissions. This may be worth mentioning in the documentation somewhere, because users typically won't have this permission by default. This can be checked with ulimit -r: if it's 0 then no realtime. On Arch, realtime can be enabled by installing the realtime-privileges package and adding yourself to the realtime group.^1

[esibun]

FWIW I think it would be worth linking to Pipewire's existing documentation and adding instructions for Arch if needed. The documentation over there is already pretty good if not discoverable: https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Performance-tuning