PartialIDctTest: reduce number of RunQuantCheck iterations
PartialIDctTest: reduce number of RunQuantCheck iterations

This currently runs 1000 * 1000 = one *million* times which is quite
unnecessary. It's one of the slowest items in Jenkins and takes over an
hour for each of the larger transforms.

Change-Id: I01653b5e610683e1a2d778ec60cf5065562ab8db

ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx