[ci] Uninstall and install packages in batch

This cuts the time for the 'Install prerequisites' step almost in half,
since it doesn't need to re-scan the apt database for every package.

.github/workflows/ci.yml

@@ -26,15 +26,17 @@ jobs:
           wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
           sudo add-apt-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy$LLVM_TAG main"
           sudo apt update
-          sudo apt install -y ninja-build
           # Remove any base dist LLVM/Clang installations
-          sudo apt remove -y "libclang*"
-          sudo apt remove -y "clang*"
-          sudo apt remove -y "llvm*"
+          sudo apt remove -y \
+               "libclang*" \
+               "clang*" \
+               "llvm*"
           # Reinstall tagged versions
-          sudo apt install -y llvm$LLVM_TAG-dev
-          sudo apt install -y libclang$LLVM_TAG-dev
-          sudo apt install -y clang$LLVM_TAG
+          sudo apt install -y \
+               ninja-build \
+               llvm$LLVM_TAG-dev \
+               libclang$LLVM_TAG-dev \
+               clang$LLVM_TAG
 
       - name: Check out default branch
         uses: actions/checkout@v2