Delete duplicated dvr tests

DvrRoutersTest tempest/api/network/test_routers.py
looks like a less commented version of the one in the
tempest/api/network/admin/test_routers_dvr.py .

The tests requires admin user,
so removing the DvrRoutersTest from the non-admin location.

The tempest/api/network/test_routers.py had an extra assert,
which is moved to tempest/api/network/admin/test_routers_dvr.py .

The two test classes looks so similar, so I suspected we duplicated it
by an internal tempest code move, but not, it was submitted separately.

Change-Id: I75c5ec4050235c79e6269ace6862be054d032821
2 files changed