LU-2776 tests: sleep longer time to yield CPU

It used to be 0.1 seconds and turned out too less.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I2776d8387aee8a55f325459999c8c9454dd2b4fa
Reviewed-on: http://review.whamcloud.com/5321
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>