Revert "Use llvm installation script from GitHub"

This reverts commit a91308e.
It is not needed any more, because the bug in the installation
file was fixed, see llvm/llvm-project#183715

Author: andreasbuhr

.github/workflows/cmake.yml

@@ -540,7 +540,7 @@ jobs:
       shell: bash
       working-directory: ${{ env.HOME }}
       run: |
-        wget https://raw.githubusercontent.com/opencollab/llvm-jenkins.debian.net/refs/heads/master/llvm.sh
+        wget https://apt.llvm.org/llvm.sh
         chmod +x llvm.sh
         sudo ./llvm.sh 22
         sudo apt-get install libc++-22-dev libc++abi-22-dev libunwind-22-dev