refactor: replace a certain kytos/mef_eline.redeployed_link_down with kytos/mef_eline.failover_link_down

[viniarck]

kytos-ng/kytos#468:

• mef_eline should publish kytos/mef_eline.failover_link_down right after installing the ingress flows and publishing the new failover flows. Currently, mef_eline is publishing a redeployed_link_down https://github.com/kytos-ng/mef_eline/blob/master/main.py#L893, but it should be replaced with kytos/mef_eline.failover_link_down in this case, just so telemetry_int will be able to efficiently get the flows upfront during this hot path event handling and install ingress related INT flow.

This also requires that issue #455 is done first since kytos/mef_eline.failover_link_down doesn't exist yet.