[usecase-wrt] Delete redundancy file in sample testapp

[Detailed commit message (if have)]
Impacted TCs num(approved): New 0, update 0, deleted 0
Unit test platform: [tizen]
Unit test result summary: xpk sample app install/launch/uninstall Pass 2, Fail 1, Blocked 0
crosswalk:crosswalk-9.37.190.0-0.i686
xpk version can not update:
https://crosswalk-project.org/jira/browse/XWALK-2290
Merge pull request #718 from linshen/misc/wrt-usecase-tizen-tests

[usecase-wrt] Delete redundancy file in sample testapp