Not all Apt::Periodic options are supported

[OrangeDog]

The file /etc/apt/apt.conf.d/10periodic is managed via the apt:unattended pillar, but not all APT::Periodic options are supported.

Those missing include, but are not limited to, MaxAge, MaxSize, and CleanInterval.

[daks]

I see that this is managed by apt/templates/unattended_config.jinja and in fact it's a 'whitelist keywords'-style, meaning that it manages a list of keywords, and do not allow every user to configure any key/value he wants.

Do we want to keep this behaviour? I'm not sure I'm in favour, it complicates maintenance and mean maintainers needs to know every usable key/value.

I see three possibilities:

1. keep current behaviour. Which means dev must be done to add those new k/v MaxAge, MaxSize, CleanInterval
2. completely change it, accepting any k/v and just looping over them to insert them in the config file. Just needs to choose between dict and list pillars, if we want to keep order or not
3. choose a mix-behaviour. Which some k/v managed individually and explicitely, but also with a loop over "additional parameters" to manage others.

1 and 3 are important if different processing is needed to manage some specific parameters.