Fix tests failing on non-mpi builds.

These tests need MPI enabled since they use D3. Fixed that. They were failing
since D3 is no longer available in non-mpi builds.

Change-Id: I5718d076858fed26d6c6a41b8c6594756cdc95f2
Merge topic '14488-fix-mpi-dependent-proxies' into next

36efd24 Fix tests failing on non-mpi builds.