Split certificate API test

Test of certificate API was written as 1 test have 2 function tests.
There is no problem during it runs successfully.
But in case of failure, we cannot find easily about which part of function
was failed. It is not less preferred.
I split the test case as 1 test case checks 1 API.

Change-Id: I679394db42aad1e6e81bf3b023a69827aaf48d70
Merge "Split certificate API test"