Summary:
Seems clean-rocksjava and clean-rocks conflict.
Also remove unnecessary step in java CI build, otherwise it will rebuild
the code again as java make sample do clean up first.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9710
Test Plan: `make rocksdbjava && make clean` should return success
Reviewed By: riversand963
Differential Revision: D35122872
Pulled By: jay-zhuang
fbshipit-source-id: 2a15b83e7a763c0fc0e42e1f35aac9551f951ece
81d1cdca7f