Removes the temporary code and tests validating the new fields setup
What does this MR do and why?
This removes the feature flag logic guarding the switch between emitting user_id and gl_user_id fields within our ApplicationContext logging. This feature flag has been switched on as of 9am UTC on 16th of October, I suspect we'll want to wait until the week beginning the 20th of October in order to merge this in order to allow for additional time to discover any issues.
References
gitlab-org/quality/quality-engineering/team-tasks#3922
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