The right way to configure Neutron to work with infrastructure MTU is by
using plugin agnostic global_physnet_mtu and ml2 specific
path_mtu/physical_network_mtus options. The deprecated option is error
prone and does not allow to use different MTUs per network.
Closes-Bug: #1603493
Related-Bug: #1549470
Related-Bug: #1542108
Related-Bug: #1542475
DocImpact Remove all references to network_device_mtu option from
Neutron documentation. Note that Nova has a deprecated option
with the same name that will need a separate patch to be removed.
Depends-On: I8e6cc99fe70d0c41a705431fb3160e8fccacff10
Depends-On: I337b284076a794027fbd63796119d56bd1923cf2
Change-Id: I7287db9df25a78a59b2dfa28acfde7fe69d17f40