Fix stress test failure for async_io (#10660)

Summary:
Sanitize initial_auto_readahead_size if its greater than max_auto_readahead_size in case of async_io

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10660

Test Plan: Ran db_stress with intitial_auto_readahead_size  greater than max_auto_readahead_size.

Reviewed By: anand1976

Differential Revision: D39408095

Pulled By: akankshamahajan15

fbshipit-source-id: 07f933242f636cfbc7ccf042e0c8b959a8ec5f3a

table/block_based/block_prefetcher.cc

@@ -45,6 +45,10 @@ void BlockPrefetcher::PrefetchIfNeeded(
     return;
   }
 
+  if (initial_auto_readahead_size_ > max_auto_readahead_size) {
+    initial_auto_readahead_size_ = max_auto_readahead_size;
+  }
+
   // In case of no_sequential_checking, it will skip the num_file_reads_ and
   // will always creates the FilePrefetchBuffer.
   if (no_sequential_checking) {
@@ -81,10 +85,6 @@ void BlockPrefetcher::PrefetchIfNeeded(
     return;
   }
 
-  if (initial_auto_readahead_size_ > max_auto_readahead_size) {
-    initial_auto_readahead_size_ = max_auto_readahead_size;
-  }
-
   if (rep->file->use_direct_io()) {
     rep->CreateFilePrefetchBufferIfNotExists(
         initial_auto_readahead_size_, max_auto_readahead_size,