[tests] don't use Gaussian labels in NetTest's TinyNet
[tests] don't use Gaussian labels in NetTest's TinyNet

Previously, labels were being nonsensically filled with a zero-mean
Gaussian. Now they are just set to constant zero. Note that this is not
necessary for TrickyNet, neither forward nor backward are ever called.

gnina/gnina,wangg12/caffe,gogartom/caffe-textmaps,wangg12/caffe,tackgeun/caffe,gnina/gnina,CZCV/s-dilation-caffe,gogartom/caffe-textmaps,longjon/caffe,longjon/caffe,tackgeun/caffe,CZCV/s-dilation-caffe,gnina/gnina,tackgeun/caffe,gogartom/caffe-textmaps,gnina/gnina,gogartom/caffe-textmaps,longjon/caffe,tackgeun/caffe,wangg12/caffe,CZCV/s-dilation-caffe,wangg12/caffe,CZCV/s-dilation-caffe,longjon/caffe,gnina/gnina,gnina/gnina