Fix caching rpm packages on CircleCI after c5ea52b

The change c5ea52b removed the step
"Generate packaged assets" which was actually not just about assets but
also about caching rpm packages. This change reintroduces the caching of
rpm packages as step "Build zypper cache".

.circleci/config.yml

@@ -6,10 +6,10 @@ orbs:
 aliases:
   - &restore_cache
     keys:
-      - v1-{{ checksum "tools/ci/ci-packages.txt" }}-{{ checksum "tools/ci/build_cache.sh" }}
+      - v2-{{ checksum "tools/ci/ci-packages.txt" }}-{{ checksum "tools/ci/build_cache.sh" }}
 
   - &save_cache
-    key: v1-{{ checksum "tools/ci/ci-packages.txt" }}-{{ checksum "tools/ci/build_cache.sh" }}
+    key: v2-{{ checksum "tools/ci/ci-packages.txt" }}-{{ checksum "tools/ci/build_cache.sh" }}
     paths:
       - "/var/cache/zypp/packages"
 
@@ -140,6 +140,12 @@ jobs:
       - restore_cache: *restore_cache
       - run: *check_cache
       - store_artifacts: *store_logs
+      - run:
+          name: "Build zypper cache"
+          command: |
+            if [ ! -d /var/cache/zypp/packages/openQA ]; then
+              bash -x tools/ci/build_cache.sh
+            fi
       - save_cache: *save_cache
 
   cache-fullstack: