[Java][CI] Pre-install the java dependencies in the dockerfile

See the comments: https://github.com/apache/arrow/blob/master/ci/docker/debian-9-java.dockerfile#L25-L28
Or perhaps just use the mounted maven m2 repository.

**Reporter**: [Krisztian Szucs](https://issues.apache.org/jira/browse/ARROW-7135) / @kszucs

_{**Note**: *This issue was originally created as [ARROW-7135](https://issues.apache.org/jira/browse/ARROW-7135). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Inspect ci/docker/debian-9-java.dockerfile around lines 25-28 and read the referenced comments first. Decide between pre-installing the Java dependencies and using the mounted Maven M2 repository; done means the CI Docker setup follows one of those approaches.

Written by the indexing model from the issue text.