Make sure that the libpam-arvados package puts its various files in the place

Make sure that the libpam-arvados package puts its various files in the place
where the pam subsystem will expect them, not inside the virtualenv.

Also, remove the code from sdk/pam/setup.py that installed a copy of the
libpam-arvados.py file under /usr/data/lib/security/libpam_arvados.py for
legacy reasons.

refs #9945
refs #15186

Arvados-DCO-1.1-Signed-off-by: Ward Vandewege <wvandewege@veritasgenetics.com>