build: add installer commit hash to /etc/harvester-release.yaml

For release builds, this should give us something like the following,
which includes the commit hash from harvester-installer:

  installer: ff64884
  os: Harvester v1.3

For local dev builds, it's a bit redundant, but I don't think
there's any harm in this:

  installer: 677447c
  os: Harvester 677447c-dirty

Related issue: harvester/harvester#6285

Signed-off-by: Tim Serong <tserong@suse.com>
(cherry picked from commit 7d89bd6)

scripts/package-harvester-os

@@ -33,6 +33,7 @@ PRETTY_NAME="Harvester ${VERSION}"
 cat > harvester-release.yaml <<EOF
 harvester: ${HARVESTER_VERSION}
 harvesterChart: ${HARVESTER_CHART_VERSION}
+installer: ${COMMIT}
 os: ${PRETTY_NAME}
 kubernetes: ${RKE2_VERSION}
 rancher: ${RANCHER_VERSION}