Robot test for RETRY during FAILOVER scenarios

This issue continues #5919.

Run scale flow/group configuration to inventory config using RESTCONF.
During ODL & Switch commnunication make RETRY/RECONCILE happen.

There are these alternative scenarios:

Scenario 1: without cluster

• run ODL single node, OVS (connected to ODL) and TCP/OF proxy
• restconf inventory config put flows/groups
• TCP/OF proxy return ERROR to ODL, but FRM starts RETRY
• TCP/OF proxy will not return ERROR to ODL after RETRY
• assertion: check flows and groups directly dump (they must be same as configure using RESTCONF)

Scenario 2: 3-node cluster RPC FlatBatch FAILOVER only

• run ODL cluster, OVS (connected to ODL) and TCP/OF proxy
• use restconf get to find out leader of the switch
• restconf inventory config put flows/groups
• disconnect switch from the leader of the switch
• assertion: check flows and groups directly dump (they must be same as configure using RESTCONF and expect that FRM made retry to the newly registered RPC)

Scenario 3a: 3-node cluster FRM FAILOVER only with 1x RESTCONF

• run ODL cluster, OVS (connected to ODL) and TCP/OF proxy
• use jolokia http get to findout which ODL node is DS master
• restconf inventory config put flows/groups
• islolate ODL node which is DS master during configuring of the Switch (TPC/OF proxy will slow down the network communication and isolate ODL DS master)
• assertion: check flows and groups directly dump (they must be same as configure using RESTCONF and expect that new master of the DS started RECONCILIATION)

Scenario 3b: 3-node cluster FRM FAILOVER only with 2x RESTCONF

• run ODL cluster, OVS (connected to ODL) and TCP/OF proxy
• use jolokia http get to findout which ODL node is DS master
• restconf on DS master inventory config put flows/groups
• islolate ODL node from another nodes (but the connectivity to the switch remains) which is DS master during configuring of the Switch (TPC/OF proxy will slow down the network communication and isolate ODL DS master).
• restconf on new DS master inventory config put flows/groups (use different test data)
• assertion: check flows and groups directly dump (they must be same as configure using RESTCONF and expect that new master of the DS started RECONCILIATION). By comparing flow/groups according to the second restconf check wether old leader has not overwritten the data.

Scenario 4: both 3-node cluster FRM FAILOVER only and RPC FlatBatch FAILOVER only

• run ODL cluster, OVS (connected to ODL) and TCP/OF proxy
• use jolokia http get to findout which ODL node is DS master
• use restconf get to find out leader of the switch
• restconf inventory config put flows/groups
• islolate ODL node which is DS master during configuring of the Switch (TPC/OF proxy will slow down the network communication and isolate ODL DS master)
• disconnect switch from the leader of the switch
• assertion: check flows and groups directly dump (they must be same as configure using RESTCONF and expect that FRM RECONCILIATION happend)

Please, use TCP/OF proxy to:

• return ERROR from the switch (socket disconnection or barrier response)
• slow down network communication between ODL and switch

Please use existing vz JSON files with flows depending on groups.

If possible reuse existing vz keywords for checking flows/group in ovs.