Update Neutron failure rate dashboard
Update Neutron failure rate dashboard

We no longer run the py35 jobs, and the coverage job is not run
in the gate, so neither shows-up on the grafana page, remove them.

Change-Id: Ibfc39a89cf8225e3c8772326893cd66e43acd054

openstack-infra/project-config,openstack-infra/project-config