Missing field name in generated sample for datastream_v1

[ohmayr]

The generated sample for datastream_v1 does not specify name as a required field which is needed to specify the project name. See the documentation: https://cloud.google.com/python/docs/reference/datastream/latest/google.cloud.datastream_v1.services.datastream.DatastreamClient#google_cloud_datastream_v1_services_datastream_DatastreamClient_update_stream.

The proto file also mentions that field to be an output only field and does not specify it to be a required field: https://github.com/googleapis/googleapis/blob/master/google/cloud/datastream/v1/datastream_resources.proto#L791.

The request to update the stream results in an error if the name field is not populated as part of the request. See: #1786