tests: drop shrink_osd from tox.ini
tests: drop shrink_osd from tox.ini

shrink_osd has its own tox config file (tox-shrink_osd.ini)

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible