Summary:
Fix the flaky test failure in error_handler_fs_test. Add the sync point, solve the dependency.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7415

Test Plan: make asan_check, ~/gtest-parallel/gtest-parallel -r 100 ./error_handler_fs_test

Reviewed By: siying

Differential Revision: D23804330

Pulled By: zhichao-cao

fbshipit-source-id: 5175108651f7652e47e15978f2a9c1669ef59d80