LU-3373 tests: small fixes for sanity tests

--test_24d fix typo
--test_24A cleanup work directory in advance
--test_27k make up message more clear
--test-framework enforce LANG to en_US

Signed-off-by: yang sheng <yang.sheng@intel.com>
Change-Id: I61c227028b44a198482b4e5c9a9f715af08c3e5f
Reviewed-on: http://review.whamcloud.com/7948
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>