service/s3/s3crypto Fix request retries

Closing and removing the temp file after send causes retry requests to
fail with an error such as:

filestore: SerializationError: failed to prepare body for retry
caused by: SerializationError: failed to reset request body
caused by: SerializationError: failed to get next request body reader
caused by: seek /tmp/213721967: file already closed

I believe the Complete handler is guaranteed to be called finally
after retries attempts have succeeded or been exhausted.

service/s3/s3crypto/helper.go

@@ -19,7 +19,7 @@ func getWriterStore(req *request.Request, path string, useTempFile bool) (io.Rea
 		return nil, err
 	}
 
-	req.Handlers.Send.PushBack(func(r *request.Request) {
+	req.Handlers.Complete.PushBack(func(r *request.Request) {
 		// Close the temp file and cleanup
 		f.Close()
 		os.Remove(f.Name())