image/jxl isn't added to the Accept: header when USE(JPEGXL) is enabled
<rdar://problem/107446115>
Pull request: https://github.com/WebKit/WebKit/pull/12212
Committed 262455@main (8778787cbaef): <https://commits.webkit.org/262455@main> Reviewed commits have been landed. Closing PR #12212 and removing active labels.