Automotive example's Dial background image has downscaling artifacts

See QTBUG-114407:

It looks like the dial's artifacts are caused by the large downscaling factor applied to the background image. It's 173x173 pixels, and the example wants it to be 128x128, down to a minimum of 64x64. The proper way to fix this is to reduce the size of the source image to 128x128. This would require updating the original .ai and .svg files. I've created QTBUG-114492 to track that.

https://bugreports.qt.io/secure/attachment/142022/automotive-windows-11-1-DPR.png

As quoted, the original .ai and .svg files need to be updated and uploaded to that server, and the generated .pngs updated in Git:

https://download.qt.io/snapshots/qqc2