Summary:
When MultiGet with the async_io option encounters an IO error in TableCache::GetTableReader, it may result in leakage of table cache handles due to queued coroutines being abandoned. This PR fixes it by ensuring any queued coroutines are run before aborting the MultiGet.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10997

Test Plan:
1. New unit test in db_basic_test
2. asan_crash

Reviewed By: pdillinger

Differential Revision: D41587244

Pulled By: anand1976

fbshipit-source-id: 900920cd3fba47cb0fc744a62facc5ffe2eccb64