Decide if mosquitto::installedBy is usefull

[github-actions]

When config key will be widely used, resolve Mosquitto installer here

jMQTT/core/class/jMQTTPlugin.class.php

Line 136 in 68f8470

// TODO: Decide if `mosquitto::installedBy` is usefull

        // Read in Core config who is supposed to have installed Mosquitto
        $res['core'] = config::byKey('mosquitto::installedBy', '', 'Unknown');
        // TODO: Decide if `mosquitto::installedBy` is usefull
        //  When config key will be widely used, resolve Mosquitto installer here
        //  labels: quality, php

        // Check if mosquitto.service has been changed by mqtt2
        if (file_exists('/lib/systemd/system/mosquitto.service')