What does this MR do and why?

Related to #478008 (closed)

After !167201 (merged) has been deployed & tested on production, we now know that metrics with time_frame array are working.

Now, we add official support for them, by making the CLI use them as the default & adding them to our documentation.

This also updates all of the tests that were previously creating a separate metric definition for each time_frame.

References

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MR acceptance checklist

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Screenshots or screen recordings

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How to set up and validate locally

To test this, run the internal events CLI:

ruby scripts/internal_events/cli.rb

And try to create new metric definition with time_frame array. Then, verify that the new metrics are working, using the Manual testing in GDK commands listed by the CLI when using the view usage command of the CLI.