Summary:
The original test nests a lot of `try` blocks. This PR flattens these blocks into independent blocks, so that each `try` block closes the DB before opening the next DB instance.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7608
Test Plan: watch the existing java tests to pass
Reviewed By: zhichao-cao
Differential Revision: D24611621
Pulled By: cheng-chang
fbshipit-source-id: d486c5d37ac25d4b860d739ef2cdd58e6064d42d
1f627210ca