The OVS Firewall has a singleton class that manages the conjuction IDs
to used in the OF rules. Those conjuntions are used to group rules
related to remote security group IDs.
Now each time the OVS agent is started, the OVS Firewall initial
conjunction ID is calculated based on the present OF rules. This value
and the next one used won't clash with any present rule in the
integration bridge during the initial transient period.
(cherry picked from commit