Do not use bootstrap handler to change session state once re-bootstrap process has been started

Creating this ticket to address these scenarios/questions:

• Currently, during the bootstrap process, the C++ client does not wait for a select_bucket response prior sending a get_cluster_config. That would appear to violate the RFC:

  This must occur prior to the cluster configuration request to ensure that a configuration containing bucket-specific context is returned.

• Some recent logs show the a new session that has not completed the bootstrap process was able to receive a response to a get_cluster_config even though it had not yet sent the get_cluster_config request w/in the bootstrap process
• How does a cluster session config update a bucket session config?
  • I assume this is correct behavior, but it would appear unclear in code how this is possible
• Some recent logs show that a session can send a KV operation that uses a bucket config that is different than the session’s config.
  • I don't think this should be happening.