python-nose: python3-nose should be default

python-nose: python3-nose should be default

We have nose recipes for both Py2 and Py3, but they both want to ship the
unversioned nosetest binary.  As Py2 is approaching EOL, remove the unversioned
binary from python-nose (leaving nosetest-2.7) instead of renaming the binary to
nosetest3 in python3-nose.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>