Pool's session persistence is deleted when HM added

[Evgeny Fedoruk]

On Neutron LBaaS v2:

Scenario:
Creating pool with session persistence data
Adding health monitor to the pool - session persistence data disappears

Following is a technical description of a bug:
create_healthmonitor_on_pool method in db layer (db/loadbalancer/loadbalancer_dbv2.py)
calls self.update_pool method with HM data on it
 In its turn, update_pool method handles both, hm and session persistence.
It deletes session persistence data if not passed.

In this case session persistence is not passed because the method was called in hm creation flow.

The result is deletion of session persistence data when adding hm to a pool

Solution:
create_healthmonitor_on_pool should probably pass current pool's session persistence data to update_pool method

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/155169

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/155169
Committed: https://git.openstack.org/cgit/openstack/neutron-lbaas/commit/?id=dea3bb77464218e84af8943883f2c023678de91e
Submitter: Jenkins
Branch: master

commit dea3bb77464218e84af8943883f2c023678de91e
Author: Brandon Logan <email address hidden>
Date: Wed Feb 11 20:43:28 2015 -0600

    Fixed bug where session persistence was removed

    Fixes bug that caused session persistence on a pool to be
    removed if a health monitor was created for that pool.

    Change-Id: I4e9a31ed8225bb3f5a2e9d902b394cefd176ee6a
    Closes-bug: #1420960