Fix failing network manager unit tests

* Instance uuid was not returned by the mocked methods of some
  network manager unit tests causing them to fail with KeyError.

Fixes bug #1204810

Change-Id: Iee04872ea954c2c59b1bf24e7cb0058c59ae8a84
Merge "Fix failing network manager unit tests"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp