Set correct nginx container value (#20641)

docker/main/rootfs/usr/local/nginx/conf/nginx.conf

@@ -109,7 +109,7 @@ http {
 
             # Use fMP4 (fragmented MP4) instead of MPEG-TS for better performance
             # Smaller segments, faster generation, better browser compatibility
-            vod_hls_segment_container fmp4;
+            vod_hls_container_format fmp4;
 
             secure_token $args;
             secure_token_types application/vnd.apple.mpegurl;