This setting does not do what it is intended to do (at least on Debian Buster):
systemd: [/etc/systemd/system/user.slice.d/puppet-override.conf:7] Memory limit '0' out of range. Ignoring.
I talked with Luca and we decided that the setting isn't really necessary. If we find it is, we need to figure out how to disable Swap some other way. The documentation at https://freedesktop.org/software/systemd/man/systemd.resource-control.html is not very helpful.