Summary:
Since `SstFileReader` don't know largest seqno of a file, it will fail this check when it open a file with global seqno: https://github.com/facebook/rocksdb/blob/ca89ac2ba997dfa0e135bd75d4ccf6f5774a7eff/table/block_based_table_reader.cc#L730
Changes:
* Pass largest_seqno=kMaxSequenceNumber from `SstFileReader` and allow it to bypass the above check.
* `BlockBasedTable::VerifyChecksum` also double check if checksum will match when excluding global seqno (this is to make the new test in sst_table_reader_test pass).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5097

Differential Revision: D14607434

Pulled By: riversand963

fbshipit-source-id: 9008599227c5fccbf9b73fee46b3bf4a1523f023