pipewire should not handle SIGINT and SIGTERM #639 those flags where maybe added in an attempt to exit the pipewire loop more gracefully, but the signals are already handled in the main loop. So it would be random if the pipewire loop or the main loop captured them. this commit removes the signal handling from the pipewire loop and extends main loop signal handling to exit normally instead of raising signal to self immediately, this means stoping audio thread and free all buffers