Decrease duration time for internally debugging the regression_script (#11283)

Summary:
Internally, the benchmark is going on hang state whereas when run on same host manually, it passes. Decrease the duration to 5s to figure out how much time it is taking to complete the benchmark.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11283

Test Plan: Ran manually internally

Reviewed By: hx235

Differential Revision: D43882260

Pulled By: akankshamahajan15

fbshipit-source-id: 9ea44164773d4df4fc05cd817b7e011426c4d428

tools/regression_test.sh

@@ -313,7 +313,7 @@ function run_db_bench {
 }
 
 function set_async_io_parameters {
-  options=" --duration=800"
+  options=" --duration=50"
   # Below parameters are used in case of async_io only.
   # 1. If you want to run below parameters for all benchmarks, it should be
   #    specify in OPTIONS_FILE instead of exporting them.