Remove faulty .assert_has_calls([])

Some UT use <mock>.assert_has_calls([]) as a way to check if mock
wasn't called - this doesn't work because assert_has_calls only checks
if passed calls are present in mock_calls and hence it is always true
regardless of whether mock was called or not. This can lead to falsely
passed tests.

Change-Id: I1be5327854cc3dc2f5b3733f2bad78200cfbbfd2
Closes-Bug: #1368234
Merge "Remove faulty .assert_has_calls([])"