Fix mysql k8s volume configuration

 The mysql:6.7 image upgrade caused the following error when deployed on GKE:
 > [ERROR] --initialize specified but the data directory has files in it. Aborting.
 Patch is based on this:  docker-library/mysql#186 (comment)

 Related to #3482

src/kubernetes/mysql/mysql-deployment.yaml

@@ -26,6 +26,8 @@ spec:
         volumeMounts:
           - name: data
             mountPath: /var/lib/mysql
+        args:
+          - "--ignore-db-dir=lost+found"
       volumes:
       - name: data
         persistentVolumeClaim: