Introduce service measurement docs

What does this MR do?

We introduced a way to measure and log any service execution (#213100 (closed)).

Since it could be very useful for other developers to enable it for some slow service in order to debug and measure execution time, number of sql calls, gc_stats, memory usage...

I added the Measuring tool in:

• https://docs.gitlab.com/ce/development/performance.html#tooling section

Related issues

Closes #218566 (closed)

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