[9.x swarm] network verification fails for env with JumboFrames

[Sergey Novikov]

Detailed bug description:
the issue was found by https://product-ci.infra.mirantis.net/job/9.x.system_test.ubuntu.jumbo_frames/174/testReport/(root)/jumbo_frames_neutron_diff_net_vxlan/

Steps to reproduce:
            1. Create cluster with neutron VXLAN
            2. Add 3 node with controller role
            3. Add 2 nodes with compute role
            4. Set mtu=9000 on private interface
            5. Deploy the cluster
            6. Run network verification
            7. Run OSTF
Expected results: all is fine
Actual result: network verification fails with

2017-01-16 02:41:33 - ERROR fuel_web_client.py:1717 -- Network verification failed:
Node Name | Node MAC address | Node Interface | Expected VLAN (not received)
slave-01_controller | 64:4f:8c:8f:d8:4b | enp0s6 | [103]

OSTF test "Check network connectivity from instance via floating IP" fails too on connectivity check http://paste.openstack.org/show/595090/

[Sergey Vasilenko (xenolog)]

I analise debug shabshot:

config for enp0s6 contains mtu=9000
config for enp0s6.103 contains mtu=9000
neutron.conf contains global_physnet_mtu=9000

config for br-mesh should not contain mtu=9000, because bridges auto adjust his MTU to minimal MTU of members.

Conclusion: All configs contains required options for passing jumbo frames.