CONTROLLER-2053 deprecates ask-based protocol, this is a follow-up to remove it from configuration and code base.

This issue covers the bits around:

1. DistributedDataStore, i.e. the frontend, which need to be removed
2. Shard (and ShardCommitCoordinator, messages, etc.) are part of the backend and need to be deprecated for removal
3. Shard should issue a stern warning when it encounters ask-based protocol.

A follow up issue will remove the backend bits in the next major release.