selftest/knownfail: Add python2 version of known fails

selftest/knownfail: Add python2 version of known fails

Post build & test running under python3 we now run with
 '--extra-python=/usr/bin/python2',  these tests will get
python2 appended to the test name so we need also to create
new knownfails for these. We will keep the python3 versions
in case we create (and we probably should) some CI job(s)
with
  PYTHON=python configure.developer --extra-python=/usr/bin/python3

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>