Update install script to cap systemd journal at 100 MB.

[crschardt]

I believe that the default for systemd journal is 4GB of logs. We might not want to let it get that big and we could cap it in journald.conf to something more manageable.

Let's cap it to a couple hundred MB? 100MB maybe? that'll take forever over the radio already. But I don't think we need a UI button to do that.

Originally posted by @mcm001 in PhotonVision/photonvision#1471 (comment)

[mcm001]

Yeah even 100MB over a 4Mbps link is dummy slow. You only need the past couple MB at most, unless the log is getting spammed by messages and hiding the boot logs.