While the case tested (`lain@ple`) gives wrong ordering due to
using only trigram to order, it almost never happens in reality. In reality
it would be either `lain` (in which case it's fine to list the user with `lain`
in display name first), or `@lain@pleroma.soykaf.com`/`lain@pleroma.soykaf.com` (which is
handled fine as well)