Update build.yml

remove other unneeded stuff

add libelf-dev to install

.github/workflows/build.yml

@@ -65,40 +65,7 @@ jobs:
           echo "CONFIG set to: $CONFIG"
 
       - name: Install ccache
-        run: sudo apt update && sudo apt install -y ccache
-
-      - name: Set up ccache
-        run: |
-          mkdir -p ~/.cache/bazel
-          ccache --version
-          ccache --max-size=2G
-          ccache --set-config=compression=true
-          echo "CCACHE_DIR=$HOME/.ccache" >> $GITHUB_ENV
-
-      - name: Download toolchain
-        run: |
-          AOSP_MIRROR=https://android.googlesource.com
-          BRANCH=main-kernel-build-2024
-          git clone $AOSP_MIRROR/kernel/prebuilts/build-tools -b $BRANCH --depth 1 kernel-build-tools
-          git clone $AOSP_MIRROR/platform/system/tools/mkbootimg -b $BRANCH --depth 1 mkbootimg
-
-      - name: Set environment variables
-        run: |
-          echo "AVBTOOL=$GITHUB_WORKSPACE/kernel-build-tools/linux-x86/bin/avbtool" >> $GITHUB_ENV
-          echo "MKBOOTIMG=$GITHUB_WORKSPACE/mkbootimg/mkbootimg.py" >> $GITHUB_ENV
-          echo "UNPACK_BOOTIMG=$GITHUB_WORKSPACE/mkbootimg/unpack_bootimg.py" >> $GITHUB_ENV
-
-      - name: Set boot sign key
-        env:
-          BOOT_SIGN_KEY: ${{ secrets.BOOT_SIGN_KEY }}
-        run: |
-          if [ ! -z "$BOOT_SIGN_KEY" ]; then
-            echo "$BOOT_SIGN_KEY" > ./kernel-build-tools/linux-x86/share/avb/testkey_rsa2048.pem
-            echo "BOOT_SIGN_KEY_PATH=$GITHUB_WORKSPACE/kernel-build-tools/linux-x86/share/avb/testkey_rsa2048.pem" >> $GITHUB_ENV
-          else
-            echo "BOOT_SIGN_KEY is not set. Using AOSP sign key..."
-            echo "BOOT_SIGN_KEY_PATH=$GITHUB_WORKSPACE/kernel-build-tools/linux-x86/share/avb/testkey_rsa2048.pem" >> $GITHUB_ENV
-          fi
+        run: sudo apt update && sudo apt install -y libelf-dev
 
       - name: Install Repo
         run: |