[usecase-webapi] Remove two unused subcase tags for usecase

Impacted TCs num(approved): New 0, Update 2, Delete 0
Unit test Platform: [Andriod]
Unit test result summary: Pass 2, Fail 0, Blocked 0
Merge pull request #807 from JianfengXu/xujf/usecase/subcase

[usecase-webapi] Remove two unused subcase tags for usecase