ci: use larger Linux runner for LTO release build on main/tags (#34029)
The release Linux build does full LTO and has been hitting out-of-memory
on the standard GitHub-hosted runner on main. This routes the
release-linux-x86_64 build to ubuntu-24.04-xl when running on
denoland/deno's main branch or on a tag, so the link step has enough
memory to complete. PRs and forks keep using the default ubuntu-24.04
runner, and the corresponding test and WPT jobs stay on the standard
runner since they don't need the extra capacity.