fix: don't build longhorn-manager twice before packaging

Longhorn 8744

Signed-off-by: Derek Su <derek.su@suse.com>
(cherry picked from commit aad527c)

scripts/package

@@ -9,7 +9,8 @@ TAG=${TAG:-${IMAGE_TAG_PREFIX}}
 REPO=${REPO:-longhornio}
 IMAGE=${IMAGE:-${REPO}/longhorn-manager:${TAG}}
 
-if [ ! -e ./bin/longhorn-manager ]; then
+if [ ! -e ./bin/longhorn-manager-amd64 ] || [ ! -e ./bin/longhorn-manager-arm64 ]; then
+    echo "Building longhorn-manager binary before packaging"
     ./scripts/build
 fi