Enable SingleDelete with user defined ts in db_bench and crash tests (#8971)

Summary:
Enable SingleDelete with user defined timestamp in db_bench,
db_stress and crash test

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8971

Test Plan:
1. For db_stress, ran the command for full duration: i) python3 -u tools/db_crashtest.py
--enable_ts whitebox --nooverwritepercent=100
ii) make crash_test_with_ts

2. For db_bench, ran:  ./db_bench -benchmarks=randomreplacekeys
-user_timestamp_size=8 -use_single_deletes=true

Reviewed By: riversand963

Differential Revision: D31246558

Pulled By: akankshamahajan15

fbshipit-source-id: 29cd8740c9921341e52f09242fca3c44d75a12b7

db_stress_tool/db_stress_test_base.cc

@@ -2782,12 +2782,6 @@ void StressTest::CheckAndSetOptionsForUserTimestamp() {
             static_cast<int>(cmp->timestamp_size()));
     exit(1);
   }
-  if (FLAGS_nooverwritepercent > 0) {
-    fprintf(stderr,
-            "-nooverwritepercent must be 0 because SingleDelete must be "
-            "disabled.\n");
-    exit(1);
-  }
   if (FLAGS_use_merge || FLAGS_use_full_merge_v1) {
     fprintf(stderr, "Merge does not support timestamp yet.\n");
     exit(1);

tools/db_crashtest.py

@@ -297,8 +297,6 @@ ts_params = {
     "user_timestamp_size": 8,
     "use_merge": 0,
     "use_full_merge_v1": 0,
-    # In order to disable SingleDelete
-    "nooverwritepercent": 0,
     "use_txn": 0,
     "read_only": 0,
     "secondary_catch_up_one_in": 0,