Summary:
* remove pyenv installation step which is not needed (it takes 3 minutes to install for every job and fail from time to time)
* download compression lib fail from time to time, Uploaded the libs to S3 and download from them for CI, which should be more stable.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9406
Test Plan: CI
Reviewed By: riversand963
Differential Revision: D33700158
Pulled By: jay-zhuang
fbshipit-source-id: be7b172d7cd059c9d7b3139fd7a34f8070460e31