Also need to update to the llvm 15 flatpak extension.
Actually Buildstream bits are on clangd 15.x already.
Pull request: https://github.com/WebKit/WebKit/pull/8567
Committed 258827@main (8196614cb062): <https://commits.webkit.org/258827@main> Reviewed commits have been landed. Closing PR #8567 and removing active labels.
<rdar://problem/104165963>
Re-opened since this is blocked by bug 250560