Set options.num_levels in db_stress_test_base (#10732)

Summary:
An add-on to https://github.com/facebook/rocksdb/pull/6818 to complete adding single-level universal compaction to stress/crash testing.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10732

Test Plan:
- Locally run for 10 min `python3 ./tools/db_crashtest.py whitebox --simple --compaction_style=1 --num_levels=1  -max_key=1000000 -value_size_mult=33 -write_buffer_size=524288 -target_file_size_base=524288 -max_bytes_for_level_base=2097152 --duration=120 --interval=10 --ops_per_thread=1000 --random_kill_odd=887`
   - Check LOG to confirm single-level universal compaction is called
- Manual testing and log checking to ensure destroy_db_initially=1 is correctly set across runs with different compaction styles (i.e, in the second half of whitebox testing).
- [ongoing]CI jobs stress test

Reviewed By: ajkr

Differential Revision: D39797612

Pulled By: ajkr

fbshipit-source-id: 16f5c40c3464c57360c06c8305f92118e426149c

db_stress_tool/db_stress_test_base.cc

@@ -3028,6 +3028,7 @@ void InitializeOptionsFromFlags(
       static_cast<ROCKSDB_NAMESPACE::CompactionStyle>(FLAGS_compaction_style);
   options.compaction_pri =
       static_cast<ROCKSDB_NAMESPACE::CompactionPri>(FLAGS_compaction_pri);
+  options.num_levels = FLAGS_num_levels;
   if (FLAGS_prefix_size >= 0) {
     options.prefix_extractor.reset(NewFixedPrefixTransform(FLAGS_prefix_size));
   }

tools/db_crashtest.py

@@ -759,7 +759,7 @@ def whitebox_crash_main(args, unknown_args):
     check_mode = 0
     kill_random_test = cmd_params["random_kill_odd"]
     kill_mode = 0
-
+    prev_compaction_style = -1
     while time.time() < exit_time:
         if check_mode == 0:
             additional_opts = {
@@ -833,6 +833,12 @@ def whitebox_crash_main(args, unknown_args):
                 "ops_per_thread": cmd_params["ops_per_thread"],
             }
 
+        cur_compaction_style = additional_opts.get("compaction_style", cmd_params.get("compaction_style", 0))
+        if prev_compaction_style != -1 and prev_compaction_style != cur_compaction_style:
+            print("`compaction_style` is changed in current run so `destroy_db_initially` is set to 1 as a short-term solution to avoid cycling through previous db of different compaction style." + "\n")
+            additional_opts["destroy_db_initially"] = 1
+        prev_compaction_style = cur_compaction_style
+
         cmd = gen_cmd(
             dict(
                 list(cmd_params.items())