dflash2 build.sh: repair a redaction placeholder that corrupted the env-parsing loop

docker-images/glm53-flash-dflash2/build.sh

@@ -10,7 +10,7 @@ cd "$(dirname "$0")"
 TAG="${TAG:-glm53-flash-dflash2:local}"
 
 ARGS=()
-while IFS <REDACTED_SECRET> -r line; do
+while IFS= read -r line; do
     case "$line" in
         ''|\#*) continue ;;
     esac