Until know, for scale issues, the creation of some NSX backend resources
for loadbalancing was postpone until the first member creation.
This complicates the code unnecessarily, since the scale issues were already resolved.
The new code will create the matching backend objects for each LBaaS/Octavia object upon creation.
In addition a DB migration is added to mark as ERROR old incomlete load balancers.
Change-Id: I2d1b9046a262fb43fd4b05e378dcf00f7f80adc0
31770cf52a