Use alembic migrations to bootstrap Monasca database

Alembic uses the monasca-agent config file for the DB
credentials. These are therefore no longer required.

Partially-Implements: blueprint monasca-roles
Change-Id: Id076e7a0b838888314159dd9e76697f89adecb5e

ansible/roles/monasca/tasks/bootstrap_service.yml

@@ -10,11 +10,6 @@
     environment:
       KOLLA_BOOTSTRAP:
       KOLLA_CONFIG_STRATEGY: "{{ config_strategy }}"
-      MONASCA_DATABASE_ADDRESS: "{{ database_address }}"
-      MONASCA_DATABASE_PORT: "{{ database_port }}"
-      MONASCA_DATABASE_USER: "{{ monasca_database_user }}"
-      MONASCA_DATABASE_PASSWORD: "{{ monasca_database_password }}"
-      MONASCA_DATABASE_NAME: "{{ monasca_database_name }}"
     image: "{{ monasca_api.image }}"
     labels:
       BOOTSTRAP: