This commit switches to a new strategy to make sure we're installing the
most recent LLVM packages. Before this commit, we used the unversioned
LLVM packages (e.g., `clang` instead of `clang-18`), which are supposed
to provide the latest snapshot, but this is broken for arm64 [1],
which we want to add in a later PR.
Anyway, the new approach is cleaner because it does not require us to
fiddle with the installed `clang` package by removing a symlink.
[1] https://github.com/llvm/llvm-project/issues/64790
Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
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