Changes the `state` field in `cloudkitty_storage_states` table. The goal is to use a more descriptive and meaningful name. The proposed new column name is `last_processed_timestamp`. Depends-on: https://review.opendev.org/c/openstack/cloudkitty/+/793973 Depends-on: https://review.opendev.org/c/openstack/cloudkitty/+/797443 Change-Id: I9e29808dc5771a6455d3c564f080e8c2ec28dc72 Implements: https://review.opendev.org/c/openstack/cloudkitty-specs/+/771513