lxc-debian: Make timezone match the host

Set timezone in container as on the host

Signed-off-by: funditus <funditus@mail.ru>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
Some tweak on previous change (timezone)

This adds the same code to the Debian-based templates (Ubuntu and Ubuntu
Cloud) and also avoids a needless fork.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>