fix: short host name for the instance label; AI VM images 683a2de

GCE의 hostname은 FQDN이라 Mimir의 instance 라벨이 legacy-2n1c.asia-northeast1-b.c....internal로
들어왔다(실측). hostname -s로 VM 이름만 쓴다. vm/ai-env/image.tag를 683a2de(hitl 진단 보존 수정)로.

vm/ai-env/image.tag

@@ -1 +1 @@
-f30af2a
+683a2de

vm/legacy-api/apply.sh

@@ -16,7 +16,7 @@ ENV_FILE=/opt/selfheal/legacy-api.env
 umask 077
 {
   printf 'DB_DSN=postgres://app:%s@10.20.0.20:5432/app?sslmode=require\n' "${DB_PASSWORD}"
-  printf 'INSTANCE=%s\n' "$(hostname)"
+  printf 'INSTANCE=%s\n' "$(hostname -s)"
 } > "$ENV_FILE"
 unset DB_PASSWORD
 docker compose --env-file "$ENV_FILE" -f compose.yaml up -d --pull always --remove-orphans

vm/postgres-common/alloy.sh

@@ -29,7 +29,7 @@ umask 077
 cat > /etc/default/alloy <<ENV
 CONFIG_FILE="/etc/alloy/config.alloy"
 CUSTOM_ARGS="--server.http.listen-addr=127.0.0.1:12345 --storage.path=/var/lib/alloy/data"
-INSTANCE="$(hostname)"
+INSTANCE="$(hostname -s)"
 PG_DSN="postgresql://harness:${PGPASSWORD}@${IP}:5432/app?sslmode=require"
 ENV
 unset PGPASSWORD