bootstrap: Support python3 on openSUSE/SLES
bootstrap: Support python3 on openSUSE/SLES

Install the correct system packages when using a python3 env. Similar
to what is done in the ubuntu/debian case.

Signed-off-by: Thomas Bechtold <146c0151a0e725bfeb02563a32ae78cab8c92198@suse.com>

dmick/teuthology,dmick/teuthology,ktdreyer/teuthology,ceph/teuthology,ceph/teuthology,ktdreyer/teuthology,SUSE/teuthology,SUSE/teuthology,dmick/teuthology,SUSE/teuthology