Plasma-systray-legacy: No gtk icons un tray... again

[Carlos A.F.]

All the gtl icons (dropbox, mega, hplip, Telegram...) does not appear in 
systray after update to plasma 5.6 in 16.04.

The package "plasma-systray-legacy" can not be installed.

"dpkg: error processing the file 
/var/cache/apt/archives/plasma-systray-legacy_0~git20151104-ded1538-2_amd64.deb 
(--unpack):
trying to overwrite `/etc/xdg/autostart/xembedsniproxy.desktop', that 
also is in the file plasma-workspace 4:5.6.4-0ubuntu1~ubuntu16.04~ppa"