Remove instrumentation class ff

What does this MR do and why?

With this MR we revert the changes done here !68808 (merged)

Related issue https://gitlab.com/gitlab-org/gitlab/-/issues/338029

We want to take a different approach without using a feature flag and allow it to deprecate the usage_data.rb

Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Service ping should be correctly generated

# generate a service ping
Gitlab::UsageData.uncached_data

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.