Kill the un-exercised tests/java dir.

The 1 test remaining appears to be covered by:
  testprojects/src/java/com/pants/testproject/unicode/main/CucumberMain.java

Which is run via:
  tests/python/pants_test/tasks/jvm_compile/java/test_java_compile_integration.py
  tests/python/pants_test/tasks/test_jvm_bundle_integration.py

https://rbcommons.com/s/twitter/r/946/