Remove an assersion about file size (#4268)

Summary:
Due to 4ea56b1b, we should also remove the
assersion in stress test. This removal can be temporary, and we can add it back
once we figure out the reason for the 0-byte SSTs.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4268

Differential Revision: D9297186

Pulled By: riversand963

fbshipit-source-id: cebba9a68f42e815f8cf24471176d2cfdf962f63

tools/db_stress.cc

@@ -1252,7 +1252,6 @@ class DbStressListener : public EventListener {
     VerifyFilePath(info.file_path);
     assert(info.job_id > 0 || FLAGS_compact_files_one_in > 0);
     if (info.status.ok()) {
-      assert(info.file_size > 0);
       assert(info.table_properties.data_size > 0);
       assert(info.table_properties.raw_key_size > 0);
       assert(info.table_properties.num_entries > 0);