[OVN] During the DB migration, allow the DB context to finish
[OVN] During the DB migration, allow the DB context to finish

During the execution of "migrate_neutron_database_to_ovn", that is
part of the OVN database migration process, the port bindings are
updated. If by any circumstance a port binding update fails, the
database write context should end properly (rolling back the
transaction) and any exception raise should be catched outside it.

Closes-Bug: #1975692
Change-Id: Idc6478e6f0fd1a2825b2c978b41feb5dab903357

mahak/neutron,openstack/neutron,mahak/neutron,openstack/neutron,mahak/neutron,openstack/neutron