Use built-in clang on macOS (#37335)

* rm extra LLVM install on macOS

* update that

* rm brew cache

* no cache

* Revert "no cache"

This reverts commit a3f8eff234935d4bb27d4bd785ad8a710496a159.

.github/workflows/tests.yaml

@@ -67,14 +67,6 @@ jobs:
       with:
         submodules: true
     - run: echo "CACHE_COMMIT_DATE=$(git log -1 --pretty='format:%cd' --date=format:'%Y-%m-%d-%H:%M')" >> $GITHUB_ENV
-    - name: Homebrew cache
-      uses: ./.github/workflows/auto-cache
-      with:
-        path: ~/Library/Caches/Homebrew
-        key: brew-macos-${{ env.CACHE_COMMIT_DATE }}-${{ github.sha }}
-        restore-keys: |
-          brew-macos-${{ env.CACHE_COMMIT_DATE }}
-          brew-macos
     - name: Install dependencies
       run: ./tools/mac_setup.sh
       env: