[Bug]: [onevpl_enctools] when add "-extbrc 1 -strict -1" on ffmpeg cmd, VBR and CBR mode output same clips

### Which component impacted?

Encode

### Is it regression? Good in old configuration?

No, this issue exist a long time

### What happened?

When setting "- extbrc 1- restrict -1", the output bitrate, md5, psnr are the same
CBR:
$ffmpeg -v verbose -hwaccel qsv -qsv_device /dev/dri/renderD128 -f rawvideo -pix_fmt yuv420p -s:v 1024x768 -r 30 -i 1024x768.yuv -frames:v 500 -c:v hevc_qsv -b:v 600000 -maxrate 600000 -extbrc 1 -strict -1 -vsync passthrough -y output.h265
VBR:
$ffmpeg -v verbose -hwaccel qsv -qsv_device /dev/dri/renderD128 -f rawvideo -pix_fmt yuv420p -s:v 1024x768 -r 30 -i 1024x768.yuv -frames:v 500 -c:v hevc_qsv -b:v 600000 -maxrate 1200000 -extbrc 1 -strict -1 -vsync passthrough -y output.h265

my test env:
OS:22.04
kernel:6.2.0-26-generic
platform:DG2 (A380)
maybe is platform-common

media-stack:
libva:https://github.com/intel/libva/commit/63d2b2232148a493d6a5b385a1ebbbd3fa37ece3
gmmlib:https://github.com/intel/gmmlib/commit/5fb4180e22695ad4e3c155cf680119913c9f44bc
media-driver:https://github.com/intel/media-driver/commit/a9f272496fc0f3e823cc4a814666ea27b443d902
libvpl:https://github.com/intel/libvpl/commit/2274efcd3672b43297ef774f332e1fed6781381c
vpl-runtime:https://github.com/oneapi-src/oneVPL-intel-gpu/commit/852fa9f705ef44c004d014548601f3804a6de705
ffmpeg:https://github.com/FFmpeg/FFmpeg/commit/3047f05a99a9189cfdcc8d904cd2bd15aaa1f162

I think this should be unrelated to the format of the output , and AV1 and AVC should also have the same problem.

### What's the usage scenario when you are seeing the problem?

Others

### What impacted?

_No response_

### Debug Information

Removing any one of "-extbrc 1 -strict -1 " would result in a different outcome, which is expected.
CBR:
$ffmpeg -v verbose -hwaccel qsv -qsv_device /dev/dri/renderD128 -f rawvideo -pix_fmt yuv420p -s:v 1024x768 -r 30 -i 1024x768.yuv -frames:v 500 -c:v hevc_qsv -b:v 600000 -maxrate 600000 -extbrc 1 -vsync passthrough -y output.h265
VBR:
$ffmpeg -v verbose -hwaccel qsv -qsv_device /dev/dri/renderD128 -f rawvideo -pix_fmt yuv420p -s:v 1024x768 -r 30 -i 1024x768.yuv -frames:v 500 -c:v hevc_qsv -b:v 600000 -maxrate 1200000 -extbrc 1 vsync passthrough -y output.h265

### Do you want to contribute a patch to fix the issue?

None