INCUS_EDK2_PATH manually set by systemd unit breaks BIOS VMs

Description:

This issue originates from a bug I filed on the Incus project Github page: #1572.
This bug report contains all the information needed to reproduce this bug.
In a nutshell, starting a BIOS VM fails, because the Arch Linux Incus package sets the INCUS_EDK2_PATH environment variable in the systemd unit, overriding Incus' own firmware detection logic.
Regarding this variable in the Arch package, Graber said the following:

Our firmware detection logic evolved quite a bit over time. There's a good chance that it wasn't initially able to find the EDK2 files on Arch.

But given that it appears to find them all just fine now, the env variable should go away.

Is there any reason this variable is set in the Arch package?
If not, removing the line:

Environment=INCUS_EDK2_PATH=/usr/share/ovmf/x64

From the file:

incus.service

Should fix this issue.