mkosi: Remove explicit /testok check

vsock should work properly after the latest release of mkosi. But
to make sure it works, let's exit with 123 in case of success and
check for that in Github Actions.

.github/workflows/mkosi.yml

@@ -121,11 +121,7 @@ jobs:
       run: mkosi --debug
 
     - name: Boot ${{ matrix.distro }} systemd-nspawn
-      run: sudo mkosi --debug boot
+      run: test "$(sudo mkosi --debug boot 1>&2; echo $?)" -eq 123
 
     - name: Boot ${{ matrix.distro }} QEMU
-      run: timeout -k 30 10m mkosi --debug qemu
-
-    # vsock in Github Actions with qemu is broken so for now we check for failures manually.
-    - name: Check ${{ matrix.distro }} QEMU
-      run: sudo mkosi shell bash -c "[[ -e /testok ]] || { cat /failed-services; exit 1; }"
+      run: timeout -k 30 10m test "$(mkosi --debug qemu 1>&2; echo $?)" -eq 123

mkosi.presets/20-final/mkosi.extra/usr/lib/systemd/mkosi-check-and-shutdown.sh

@@ -1,8 +1,6 @@
 #!/bin/bash -eux
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
-rm -f /testok
-
 # TODO: Figure out why this is failing
 systemctl reset-failed systemd-vconsole-setup.service
 
@@ -20,4 +18,6 @@ fi
 # Exit with non-zero EC if the /failed-services file is not empty (we have -e set)
 [[ ! -s /failed-services ]]
 
-touch /testok
+# On success, exit with 123 so that we can check that we receive the actual exit code from the script on the
+# host.
+exit 123