release/azure: Don't use azure-agent deprovision to build image

Deprovision feature of waagent is used for preparing to capture a
running VM and turn it into a VM image.  Using it in the process of
building a VM image from scratch will cause some side effects such as
the hostname of the building host getting reset.

Remove calling the deprovision command and use a simpler way to fulfill
the requirements of the Azure VM image.

Sponsored by:	The FreeBSD Foundation

release/tools/azure.conf

@@ -20,17 +20,19 @@ export NOSWAP=YES
 export VM_BOOTPARTSOFFSET=1M
 
 vm_extra_pre_umount() {
+	mount -t devfs devfs ${DESTDIR}/dev
+
 	# The firstboot_pkgs rc.d script will download the repository
 	# catalogue and install or update pkg when the instance first
 	# launches, so these files would just be replaced anyway; removing
 	# them from the image allows it to boot faster.
-	mount -t devfs devfs ${DESTDIR}/dev
 	chroot ${DESTDIR} ${EMULATOR} env ASSUME_ALWAYS_YES=yes \
 		/usr/sbin/pkg delete -f -y pkg
-	umount ${DESTDIR}/dev
 	rm ${DESTDIR}/var/db/pkg/repo-*.sqlite
 
-	yes | chroot ${DESTDIR} ${EMULATOR} /usr/local/sbin/waagent -deprovision
+	chroot ${DESTDIR} ${EMULATOR} pw usermod root -h -
+
+	umount ${DESTDIR}/dev
 
 	cat << EOF >> ${DESTDIR}/etc/rc.conf
 ifconfig_hn0="SYNCDHCP"