heat tests : CFN_API functional tests NoEcho Parameters fix

NoEcho is now implemented in the engine for parameters, so we
need to change the expected ParameterValues to '******' to match
the API response for the NoEcho==True parameters

Change-Id: I4f50633dc5358e8779bfbaf03dda2f7fe1b7d452
Signed-off-by: Steven Hardy <shardy@redhat.com>