testcase start service script fail on centos env

testcase start service script fail on centos env

JIRA: YARDSTICK-676

In the HA test cases, script 'start_serice.bash' is used to restart the OpenStack service to recover killed process.
It uses 'lsb_release' command to determine the host linux distribution and the target Openstack service name.
In some environments, the 'lsb_release' is not installed hence will cause process-recovery failure.

This patch states the software precondions in the HA test case descriptions.

Change-Id: Ie3f503b8185deec13eebbcacbeac57c0a018cb73
Signed-off-by: JingLu5 <lvjing5@huawei.com>