Allow consecutive SingleDelete() in stress/crash test (#9930)

Summary:
We need to support consecutive SingleDelete(), so this PR adds it to the stress/crash tests.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9930

Test Plan: `python3 tools/db_crashtest.py blackbox --simple --nooverwritepercent=50 --writepercent=90 --delpercent=10 --readpercent=0 --prefixpercent=0 --delrangepercent=0 --iterpercent=0 --max_key=1000000 --duration=3600 --interval=10 --write_buffer_size=1048576 --target_file_size_base=1048576 --max_bytes_for_level_base=4194304 --value_size_mult=33`

Reviewed By: riversand963

Differential Revision: D36081863

Pulled By: ajkr

fbshipit-source-id: 3566cdbaed375b8003126fc298968eb1a854317f

db_stress_tool/no_batched_ops_stress.cc

@@ -632,33 +632,14 @@ class NonBatchedOpsStressTest : public StressTest {
   Status TestDelete(ThreadState* thread, WriteOptions& write_opts,
                     const std::vector<int>& rand_column_families,
                     const std::vector<int64_t>& rand_keys,
-                    std::unique_ptr<MutexLock>& lock) override {
+                    std::unique_ptr<MutexLock>& /* lock */) override {
     int64_t rand_key = rand_keys[0];
     int rand_column_family = rand_column_families[0];
     auto shared = thread->shared;
-    int64_t max_key = shared->GetMaxKey();
 
     // OPERATION delete
-    // If the chosen key does not allow overwrite and it does not exist,
-    // choose another key.
-    std::string write_ts_str;
-    Slice write_ts;
-    while (!shared->AllowsOverwrite(rand_key) &&
-           !shared->Exists(rand_column_family, rand_key)) {
-      lock.reset();
-      rand_key = thread->rand.Next() % max_key;
-      rand_column_family = thread->rand.Next() % FLAGS_column_families;
-      lock.reset(
-          new MutexLock(shared->GetMutexForKey(rand_column_family, rand_key)));
-      if (FLAGS_user_timestamp_size > 0) {
-        write_ts_str = NowNanosStr();
-        write_ts = write_ts_str;
-      }
-    }
-    if (write_ts.size() == 0 && FLAGS_user_timestamp_size) {
-      write_ts_str = NowNanosStr();
-      write_ts = write_ts_str;
-    }
+    std::string write_ts_str = NowNanosStr();
+    Slice write_ts = write_ts_str;
 
     std::string key_str = Key(rand_key);
     Slice key = key_str;