Summary:
* Fixes a Java test compilation issue on macOS
* Cleans up CircleCI RocksDBJava build config
* Adds CircleCI for RocksDBJava on MacOS
* Ensures backwards compatibility with older macOS via CircleCI
* Fixes RocksJava static builds ordering
* Adds missing RocksJava static builds to CircleCI for Mac and Linux
* Improves parallelism in RocksJava builds
* Reduces the size of the machines used for RocksJava CircleCI as they don't need to be so large (Saves credits)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7769
Reviewed By: akankshamahajan15
Differential Revision: D25601293
Pulled By: pdillinger
fbshipit-source-id: 0a0bb9906f65438fe143487d78e37e1947364d08