Java: Don't put gradle files in parent directory of output

[Garrett Jones]

Java generation will dump gradle files into the parent directory of the output. This is somewhat rude, and could even be dangerous if it overwrites user files that they don't want overwritten.

[Hanzhen Yi]

With bazel in place we should just stop generating gradle files.

[hkdevandla]

This is will closed as part of the Java Microgenerator.