Abort verification when expected state has pending writes / db return non OK(NotFound) status (#12232)

Summary:
In the current flow, the verification will pass and continue the test when db return non Ok(NotFound) status while expected state has pending writes.

fdfd044bb2/db_stress_tool/no_batched_ops_stress.cc (L2054-L2065)

We can just abort when such a db status is ever encountered. This can prevent follow up tests like `TestCheckpoint` and `TestBackupRestore` to consider such a key as existing in the db via the `ExpectedState::Exists` API. This could be a reason for some recent test failures in this path.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12232

Reviewed By: cbi42

Differential Revision: D52737393

Pulled By: jowlyzhang

fbshipit-source-id: f2658c5332ccd42f6190783960e2dc6fcd81ccc5

db_stress_tool/no_batched_ops_stress.cc

@@ -2057,11 +2057,12 @@ class NonBatchedOpsStressTest : public StressTest {
         Slice slice(value_from_db);
         uint32_t value_base = GetValueBase(slice);
         shared->SyncPut(cf, key, value_base);
+        return true;
       } else if (s.IsNotFound()) {
         // Value doesn't exist in db, update state to reflect that
         shared->SyncDelete(cf, key);
+        return true;
       }
-      return true;
     }
     char expected_value_data[kValueMaxLen];
     size_t expected_value_data_size =