ceilometer-dbsync shouldn't still create alarm tables

[Liusheng]

since we have remove alarm out of ceilometer code tree, but if wen run ceilometer-dbsync, the alarm tables will still be created, we need to add migration script to remove the alarm tables.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/312399

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/312399
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=800034dc0bbb9502893dedd9bcde7c170780c375
Submitter: Jenkins
Branch: master

commit 800034dc0bbb9502893dedd9bcde7c170780c375
Author: liusheng <email address hidden>
Date: Wed May 4 17:18:49 2016 +0800

    Add a tool to clean the legacy alarm tables

    Since we have moved alarm out of ceilometer, when run ceilometer-dbsync,
    the alarm tables will still be created and won't be removed. This change
    added a tool that allow users to drop the legacy alarm and alarm_history
    tables with SQL backends.

    Change-Id: Ia831741319fd8e198f54a7d4a99b4d7833074e8e
    Closes-Bug: #1578128
    Signed-off-by: liusheng <email address hidden>

[Davanum Srinivas (DIMS) (dims-v)]

This issue was fixed in the openstack/ceilometer 7.0.0.0b2 development milestone.