LU-4206 tests: cancel data lock before ELC test

Since 2,4, MDT will send unlink request to the OST, and OST
will destroy the object and revoke the data lock in the client
cache, i.e. client will not do ELC for data lock during the
rename and unlink. So cancel the data lock before couting
lock block callback counting.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ib216d068e71dce8236f26cb62188fff6d090042a
Reviewed-on: http://review.whamcloud.com/10250
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>