Remove work around change for test_port_forwarding

Changes in neutron repo for HashRing caching [1] address the
work around added to the octavia functional test. And because
of that, the in-memory db can be used reliably once again.

This change partially reverts commit b68d2a78a4

[1]: https://review.opendev.org/c/openstack/neutron/+/765874

Depends-On: https://review.opendev.org/#/c/765874/
Change-Id: Ifaf376c92d99f17f96e2c9ead2528fea3cf65070

tox.ini

@@ -38,9 +38,6 @@ setenv =
   {[testenv]setenv}
   OS_TEST_PATH=./ovn_octavia_provider/tests/functional
   OS_TEST_TIMEOUT=240
-  # TODO(flaviof): remove line below when issue with in-memory db is fixed
-  #                and functional works w/out this workaround.
-  OS_TEST_DBAPI_ADMIN_CONNECTION=sqlite:///sqlite.db
 deps = {[testenv]deps}
        -r{toxinidir}/ovn_octavia_provider/tests/functional/requirements.txt