re-use the same local drive used by remote-peer (#18645)

historically, we have always kept storage-rest-server
and a local storage API separate without much trouble,
since they both can independently operate due to no
special state() between them.

however, over some time, we have added state()
such as

- drive monitoring threads now there will be "2" of
  them per drive instead of just 1.

- concurrent tokens available per drive are now twice
  instead of just single shared, allowing unexpectedly
  high amount of I/O to go through.

- applying serialization by using walkMutexes can now
  be adequately honored for both remote callers and local
  callers.

cmd/bucket-handlers.go

@@ -1657,9 +1657,11 @@ func (api objectAPIHandlers) DeleteBucketHandler(w http.ResponseWriter, r *http.
 	}
 
 	// Return an error if the bucket does not exist
-	if _, err := objectAPI.GetBucketInfo(ctx, bucket, BucketOptions{}); err != nil && !forceDelete {
-		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
-		return
+	if !forceDelete {
+		if _, err := objectAPI.GetBucketInfo(ctx, bucket, BucketOptions{}); err != nil {
+			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
+			return
+		}
 	}
 
 	// Attempt to delete bucket.