ci: stabilize dind cache and buildx lifecycle per run

Jenkinsfile

@@ -69,8 +69,7 @@ spec:
     - name: docker-config-writable
       emptyDir: {}
     - name: dind-storage
-      persistentVolumeClaim:
-        claimName: jenkins-dind-cache
+      emptyDir: {}
     - name: harbor-config
       secret:
         secretName: harbor-robot-pipeline
@@ -190,12 +189,10 @@ spec:
               exit 1
             fi
             docker run --privileged --rm tonistiigi/binfmt --install amd64,arm64
-            if docker buildx inspect metis-builder >/dev/null 2>&1; then
-              docker buildx use metis-builder
-            else
-              docker buildx create --name metis-builder --driver docker-container --use
-            fi
-            docker buildx inspect --bootstrap
+            BUILDER_NAME="metis-builder-${BUILD_NUMBER}"
+            docker buildx rm "${BUILDER_NAME}" >/dev/null 2>&1 || true
+            docker buildx create --name "${BUILDER_NAME}" --driver docker-container --use
+            docker buildx inspect "${BUILDER_NAME}" --bootstrap
           '''
         }
       }