Description of problem:
[Host QoS] - Engine should set a default link share traffic shaping on networks that attached to the ovirtmgmt's interface. 

We should set some default link share(ls) on networks that attached to the ovirtmgmt's interface, let say ls=50(keep some default ratio) between the networks.
We should do this for user/admin, cause currently there is no meaning to the default traffic shaping we setting on the ovirtmgmt network, unless the other networks on this NIC have some host QoS defined as well. 
See BZ - 1255474 [RFE][SCALE] traffic shaping on ovirtmgmt interface

Version-Release number of selected component (if applicable):
4.0.0.4-0.1.el7ev

How reproducible:
100

Steps to Reproduce:
1. Add host to rhev-m  
2. Attach 2 vlan networks(v1, v2) to the ovirtmgmt's interface
3. Send traffic over the 3 networks

Actual results:
The default host QoS that is defined over the management network(ls=50), has no meaning and it's not forced. 

For example, for a 1Gb NIC: 
ovirtmgmt -
[  3] 10.0-11.0 sec  38.5 MBytes   323 Mbits/sec

v1 -
[  3] 10.0-11.0 sec  37.2 MBytes   312 Mbits/sec

v2 -
[  3] 10.0-11.0 sec  37.5 MBytes   315 Mbits/sec


Expected results:
This would work only if the other 2 vlan networks had some link share defined(at least)

Additional info:
See RFE - 1255474