Avoids docker.io pulls from testcontainers (and removes a JDK install) (#3290)
Avoids docker.io pulls from testcontainers (and removes a JDK install) (#3290)

This avoids docker.io pulls implicitly done by testcontainers, in order
to prvent build outages due to pull limits.

This also removes a redundant JDK 11 install step, to speed up Travis.
twitter/zipkin,openzipkin/zipkin,openzipkin/zipkin,twitter/zipkin,adriancole/zipkin,openzipkin/zipkin,twitter/zipkin,openzipkin/zipkin,twitter/zipkin,openzipkin/zipkin,adriancole/zipkin,adriancole/zipkin,adriancole/zipkin