gpdpocket-audio: use pulse/daemon.conf.d instead of diversions

[dario23]

for (at least some of the) config files installed, we could do without dpkg-diverting the original config for our own by using .conf.d subdirectories, one example being the pulse daemon.conf that is installed. instead of diverting away the whole daemon.conf (currently without referencing the original one again, so users miss all future updates to that file) we could create a separate file etc/pulse/daemon.conf.d/90-gpdpocket-no-realtime.conf with just

realtime-scheduling = no

in it. the pulse-daemon.conf(5) man page says the files in daemon.conf.d are read after daemon.conf, so settings in our new file would take precedence over any system settings in daemon.conf, but having gpdpocket-audio package installed wouldn't mean missing other pulse updates anymore.