Restore Cirrus-CI boot smoke test

This reverts commit a7d593dd1d.
We now use compute_engine_instance which allows us to specify a custom
disk size.  Also go back to using the default qemu version (rather than
qemu42 or qemu-devel) as any issues were fixed some time ago.

Reviewed by:	lwhsu, markj
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D30082

.cirrus.yml

@@ -1,11 +1,14 @@
 # $FreeBSD$
 
-freebsd_instance:
+compute_engine_instance:
   # Image list available via
   # gcloud compute images list --project freebsd-org-cloud-dev --no-standard-images
+  platform: freebsd
+  image_project: freebsd-org-cloud-dev
   image: freebsd-13-0-release-amd64
   cpu: 8
   memory: 24G
+  disk: 40
 
 env:
   CIRRUS_CLONE_DEPTH: 1
@@ -13,7 +16,7 @@ env:
 task:
   timeout_in: 120m
   install_script:
-  - pkg install -y llvm12
+  - pkg install -y qemu uefi-edk2-qemu-x86_64 llvm12
   setup_script:
   - uname -a
   - df -m
@@ -22,6 +25,10 @@ task:
   - chown user:user /usr/obj/$(pwd -P)
   script:
   - su user -c "make -j$(sysctl -n hw.ncpu) CROSS_TOOLCHAIN=llvm12 WITHOUT_TOOLCHAIN=yes buildworld buildkernel"
+  package_script:
+  - su user -c "make CROSS_TOOLCHAIN=llvm12 WITHOUT_TOOLCHAIN=yes PKG_FORMAT=tar packages"
+  test_script:
+  - sh tools/boot/ci-qemu-test.sh
   post_script:
   - df -m
   - du -m -s /usr/obj