[beta] Revert "Build shared LLVM lib for windows-gnullvm"

[mati865]

This reverts commit 1d1280a.

Reapply #155285 to the new beta because #156229 missed the train by a couple of hours.

[rustbot]

Warning

If you are changing how CI LLVM is built or linked, make sure to bump
src/bootstrap/download-ci-llvm-stamp.

cc @jieyouxu

[rustbot]

r? @Mark-Simulacrum

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Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: infra-ci
• infra-ci expanded to Kobzol, Mark-Simulacrum, jdno, jieyouxu, marcoieni
• Random selection from Mark-Simulacrum, jdno, marcoieni

[rustbot]

⚠️ Warning ⚠️

• Pull requests are usually filed against the main branch for this repo, but this one is against beta. Please double check that you specified the right target!

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

  PR_CI_JOB: 1
  SKIP_SUBMODULES: src/gcc
  IMAGE: tidy
##[endgroup]
error: PRs changing the `nightly` channel should be sent to the `main` branch!
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"
echo "disk usage:"
df -h
shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}

[mati865]

I edited the title, but perhaps it got lost when I changed the target branch because it caused the page to reload (although the modified description remained modified).