Summary:
These tests would frequently fail to find SST files due to race
condition in running ldb (read-only) on an open DB which might do automatic
compaction. But only sometimes would that failure translate into test
failure because the implementation of ldb file_checksum_dump would
swallow many errors. Now,
* DB closed while running ldb to avoid unnecessary race condition
* Detect and report/propagate more failures in `ldb file_checksum_dump`
* Use --hex so that random binary data is not printed to console
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8898
Test Plan: ./ldb_cmd_test --gtest_filter=*Checksum* --gtest_repeat=100
Reviewed By: zhichao-cao
Differential Revision: D30848738
Pulled By: pdillinger
fbshipit-source-id: 20290b517eeceba99bb538bb5a17088f7e878405