Don't create TransactionalProducer if all statements in request are non-distributed

[stevenpyzhang]

Is your feature request related to a problem? Please describe.
#3660 introduced a Transactional Producer protocol to the command topic. A new producer is created for every request to the KsqlResource, even if the statements don't need to be enqueued in the command topic.

Describe the solution you'd like
Make the Transactional Producer an optional. When a request is received, parse all the statements and search through them to see if a distributed statement is present. If it is, create a Transactional Producer.

[stevenpyzhang]

This isn't an issue anymore since the producer has been moved to only be created in the DistributingExecutor.