Only the owner should see builder / reviewbot messages

Change-Id: I30a30e7248d4e3c22681308cd2c4b432f5bb7e52
this is for both old and new screen, the point is to help reviewers to view past discussions more like a conversation and to encourage them to read what has been discussed before, otherwise for a change with a lot of patchsets, 3-4 builds, there are a lot of extra lines that are not really important for the review process, don't you agree?