Kafka codestart causes problems - and we install kafka when not used

[holly-cummins]

There is a missing guard on this, in the non-messaging paths:

[source,shell,subs="attributes+"]
----
./mvnw io.quarkus:quarkus-maven-plugin:{quarkus-version}:create \
  -DplatformVersion={quarkus-version} \
  -DprojectGroupId=io.quarkus.workshop.super-heroes \
  -DprojectArtifactId=rest-fights \
  -DclassName="io.quarkus.workshop.superheroes.fight.FightResource" \
  -Dpath="api/fights" \
  -Dextensions="jdbc-postgresql,hibernate-orm-panache,hibernate-validator,quarkus-resteasy-reactive-jackson,smallrye-openapi,kafka"
----

Also, when we do install kafka, @maxandersen has spotted that the codestart causes problems, so we need to specify --no-codestart.