OBS WHIP: No video on FLV

[rscataran]

Describe the bug Using OBS WHIP ang enabling DVR, the FLV file saved does not have a video stream. audio only.

Version SRS/5.0.205

To Reproduce Steps to reproduce the behavior:

1. Using conf\rtmp2rtc.conf as base.
2. enable DVR by including on vhost

   
   dvr {
       enabled     on;
       dvr_path    D:/SRS/data/[app]/[stream].[timestamp].flv;
   }

3. Start OBS, set stream to WHIP, with server `http://localhost:1985/rtc/v1/whip/?app=live&stream=livestream`
4. Start Streaming, then stop after a few seconds.
5. Open recorded FLV file in VLC, audio only will be played.
- SRS LivePlayer also does not show the video

**Expected behavior**
Video and audio should be recorded

**Screenshots**
![image](https://github.com/ossrs/srs/assets/13414746/10134968-e505-4812-b3c9-7e45f1444886)
![image](https://github.com/ossrs/srs/assets/13414746/65733eb0-439e-44aa-b8aa-9be620de0d02)

**Additional context**
Using SRS WHIP Player Publish, produces FLV file that has both video and audio.

[rscataran]

I tried to add

has_audio on; has_video on; guess_has_av off;

Under http_remux to try and force the FLV headers to have video and audio,

then the FLV file does not play using SRS LivePlayer.

[winlinvip]

Dup to https://github.com/ossrs/srs/pull/3920