Add timing profile for each unit test

[vkuznet]

No description provided.

[yuyiguo]

@vkuznet

I don't think individual test timing has any meaning in DBS unit tests. This individual test mainly for cover different use cases. Each API speed is more depending on the DB load and the server load at the time it is executed. However, the overall speed does reflect some underline problems.

Adding individual timing may mislead the testers. So I will not commit the PR.

[vkuznet]

Yuyi, it is up to you, I only put PR to make it clear how I get those timing numbers. It also helped me to understand the difference in APIs. Will you use it or not it is totally your decision, but I felt it would be better documented (even as closed issue).