Revert "Disable limestone provider due to IPv4-less nodes"
Revert "Disable limestone provider due to IPv4-less nodes"

This reverts commit ef5cc142057b7dbb4bf9bcb9d8ef219be158c92d.

We now automatically discard nodes which lack working IPv4
connectivity, the condition which was previously causing occasional
failures in this provider.

Change-Id: I7a7db0dbc1ff6203855eb5dee40d234a26335db0

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