Kolla have updated the RabbitMQ image version from 3.11 to 3.12. While
in 3.12, there are a few feature flags that is marked as required [1].
If those are not enable, RabbitMQ will fail to start after upgrade.
This commit added additional required feature flags to the
rabbitmq_feature_flags list.
[1] https://www.rabbitmq.com/feature-flags.html#core-feature-flags
Change-Id: I401bbaae059bca5c656269f65ac8b7bff0aefae2
c5d314d979