clear etcd after migration

[vishal-chdhry]

No description provided.

[vishal-chdhry]

currently, a retry watcher is used for migration, therefore when reports are cleaned up from etcd, that will send delete events to reports-server as well which will clean up reports from reports server as well

[iusergii]

Does the reports-server clean up etcd after migration, or is it only responsible for cleaning up its own data in response to delete events from etcd? Do we need any post-migration cleanup?