"HandleLidSwitchExternalPower= is completely ignored by default (for backwards compatibility)"[1]

I noticed (with help in IRC) that my laptop wasn't suspending on lid close when plugged in and charging, which I hadn't seen happen on other systems. I now know that I can set this by configuring the `elogind-service` parameter `handle-lid-switch-external-power`. Regardless, it seems like it should default to being unset rather than set/ignored, since that would heed the line I quoted above.

[1]: https://www.freedesktop.org/software/systemd/man/logind.conf.html