daemons: pid/asok files are not removed upon daemon normal exit
After stopping the the daemon, the corresponding pid/asok files are not automatically removed, there is a fix 24eb5647685ebba5e04e0171fae24033badca656 around that, but that looks more like a work-around (and hide the original problem) rather than a fix.
For asok file, it should be removed as part of CephContext's destructor.
For pid file, it should be removed by the atexist handler.
The reason why they don't get removed needs more investigation..