x264 does not respect "Ignore streaming service setting recommendations" for buffer size, if a custom buffer size is used

Operating System Info

Windows 10

OBS Studio Version

30.0.0

OBS Studio Log URL

https://obsproject.com/logs/NX11ztdDwtYUQjXv

Expected Behavior

VBV_Bufsize of the video file should reflect the used buffer size value if ignore limits is checked

Current Behavior

VBV_Bufsize of the video file is forced to 6000 if a greater value then that is used, even when the user has checked "Ignore streaming service setting recommendations"
The checkbox works fine for bitrate, but not for buffer size.

Relevant log part:

User is ignoring service bitrate limits.
buffer size:  6000

I've also verified the video file with mediainfo for the metadata, which indeed shows vbv_bufsize at 6000
If no custom buffer size is used, and ignore limits is checked, a greater then 6000 bitrate will also allow for a greater buffer size

Steps to Reproduce

1. Go to Settings > Stream
2. Select Twitch
3. Check box for "Ignore streaming service setting recommendations"
4. Go to Settings > Output
5. Select Output Mode > Advanced
6. Select Video Encoder > x264
7. Check Box for "Use Custom Buffer Size" under "Encoder Settings"
8. Enter any value that is greater then 6000 into the Buffer Size field

Start by reproducing the issue using the listed OBS Stream and Output settings, then inspect the x264 encoder-settings path responsible for the reported buffer size. Use the provided log and MediaInfo result to compare custom values above 6000 with the ignore-recommendations option; done means the resulting VBV_Bufsize honors the custom value and the existing behavior remains correct otherwise.