This is the second part to support `Google Cloud Storage` offload. 
It aims to replace "s3 client" api with "jclouds" api, and make sure unit test and integration test passed.
There will be a following change to add `Google Cloud Storage` support and related test.

change:
replace `s3client` api with `jclouds` related api in `S3ManagedLedgerOffloader`

Master Issue: #2067