chore(ci): get rid of cache buildroot (#1014) (#1077)

Signed-off-by: madomado <madonuko@outlook.com>
(cherry picked from commit 32363b1fec)

.github/workflows/autobuild.yml

@@ -54,13 +54,6 @@ jobs:
       - name: Set up git repository
         run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
 
-      - name: Cache buildroot
-        id: br-cache
-        uses: actions/cache@v3
-        with:
-          path: /var/cache
-          key: ${{ runner.os }}-br-${{ matrix.version }}-${{ matrix.pkg.arch }}
-
       - name: Include custom build template instead of package default
         run: |
           cp -v anda/terra/mock-configs/terra.tpl /etc/mock/templates/terra.tpl