Summary:
Fix the nested quotes for CRASH_TEST_EXT_ARGS, as the generated json could not be parsed by the sandcastle job.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4243
Differential Revision: D9228429
Pulled By: anand1976
fbshipit-source-id: 3c2bcac34870e377949d8a79c55e33b8363b25dd