This test is to verify DNE2 clients can work with 2.5/2.7 servers.
For DNE2 client, it can use this build
https://build.hpdd.intel.com/job/lustre-reviews/32529/
2.5/2.7 server can use the most update rpm in the build.
https://build.hpdd.intel.com

Right now, we can check these two things.
1. Sanity should pass as other inter-op test.
2. check if "lfs mkdir" and "lfs mv" works in this environment. Note: if DNE2 clients tries to create a striped directory on 2.5 servers. 2.5 server should return -EINVAL or EIO error, but DNE2 clients should be able to create striped directory on 2.7 servers.