This reverts the i386 part of r342283, "Rework UEFI ESP generation", and
the followup commit in r342690.
r342283 added an ESP to the i386 memstick image, and as a side effect
made the ESP the active partition, not the bootcode-containing UFS
partition. As a result the i386 memstick images would not boot in
either UEFI or legacy mode - UEFI failed because we do not support i386
UEFI booting, and legacy mode failed because the partition with legacy
bootcode was not active.
The bootcode-containing UFS partition is again the only, and active,
partition.
PR: 246494
Reported by: Jorge Maidana
Differential Revision: The FreeBSD Foundation
7cb9390a38