Updates for 'test_scale_group_2.py' should be add to stable/mitaka from master branch

[Tatyana Kuterina]

Detailed bug description:
Fix for issue in checks(see below) is already present on master branch. It should be add on branch stable/mitaka.

Found on CI:
https://product-ci.infra.mirantis.net/job/9.x.acceptance.ubuntu.ha_scale_group_2/2/console

Test: Deploy cluster with 3 controllers, remove 2 controllers and re-deploy, check hosts and corosync
Test Group: remove_controllers

Steps to reproduce:
        1. Create cluster
        2. Add 3 controller, 1 compute
        3. Deploy the cluster
        4. Remove 2 controllers
        5. Deploy changes
        6. Run OSTF
        7. Verify networks
        8. Check /etc/hosts that removed nodes aren't present
        9. Check corosync.conf that removed nodes aren't present
Expected results:
  Environment is deployed, checks are finished without errors
Actual result:
  Environment is deployed but checks are finished with errors
   UnexpectedExitCode: Command 'grep 'node-1.test.domain.local' /etc/hosts' returned unexpected exit code 1, while waiting for [0]

Description of the environment:
 9.1 snapshot #93

FUEL_QA_COMMIT=870dbbe7a6c9186cc3512f671d9292a2123aa35f
UBUNTU_MIRROR_ID=ubuntu-2016-08-03-174238
CENTOS_MIRROR_ID=centos-7.2.1511-2016-05-31-083834
MOS_UBUNTU_MIRROR_ID=9.0-2016-08-04-084321
MOS_CENTOS_OS_MIRROR_ID=os-2016-06-23-135731
MOS_CENTOS_PROPOSED_MIRROR_ID=proposed-2016-08-04-102320
MOS_CENTOS_UPDATES_MIRROR_ID=updates-2016-06-23-135916
MOS_CENTOS_HOLDBACK_MIRROR_ID=holdback-2016-06-23-140047
MOS_CENTOS_HOTFIX_MIRROR_ID=hotfix-2016-07-18-162958
MOS_CENTOS_SECURITY_MIRROR_ID=security-2016-06-23-140002

https://drive.google.com/a/mirantis.com/file/d/0Bz15vbpS5ZPNSlJaTlktVHFrVlU/view?usp=sharing

[Dmitry Belyaninov (dbelyaninov)]

again:
https://product-ci.infra.mirantis.net/job/9.x.acceptance.ubuntu.ha_scale_group_2/12/testReport/(root)/remove_controllers/remove_controllers/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/380970
Committed: https://git.openstack.org/cgit/openstack/fuel-qa/commit/?id=51681dfdbb035e3d2a32d2e33169d298e90bd900
Submitter: Jenkins
Branch: stable/mitaka

commit 51681dfdbb035e3d2a32d2e33169d298e90bd900
Author: Valentyn Yakovlev <email address hidden>
Date: Mon Oct 3 11:06:34 2016 +0300

    Fix for expect result in 'grep'
    Fix scenario steps

    Change-Id: I100e59b614fe91965ba5af90fece7f27019ce250
    Closes-bug: #1610145