ci-automation/vms: Export official release variable

The official release variable is used to decide whether a build ID gets
appended to the FLATCAR_VERSION (or VERSION in os-release) or not. It
was set for the image job but not for the vms job, causing the
build_sysext script to get the build ID appended to the FLATCAR_VERSION
which causes a mismatch with the one from the image job.
Set the official release variable in the vms job as well.

ci-automation/vms.sh

@@ -62,6 +62,7 @@ function _vm_build_impl() {
     shift
     # $@ now contains image formats to build
 
+    source sdk_lib/sdk_container_common.sh
     source ci-automation/ci_automation_common.sh
     source ci-automation/gpg_setup.sh
 
@@ -102,6 +103,12 @@ function _vm_build_impl() {
     # Keep compatibility with SDK scripts where "equinix_metal" remains unknown.
     formats=$(echo "$formats" | tr ' ' '\n' | sed 's/equinix_metal/packet/g')
 
+    if is_official "${vernum}"; then
+        export COREOS_OFFICIAL=1
+    else
+        export COREOS_OFFICIAL=0
+    fi
+
     local images_in="images-in/"
     local file
     rm -rf "${images_in}"