Update docs on debug logging permissions

What does this MR do?

The docs imply that the user has to enable some kind of setting so that debug logging permissions are restricted to Developers and above. This used to be a feature flag, but it has been enabled by default and already removed. Additionally, these permissions docs also state that "View a job with debug logging" are already restricted to Developers and above. There are no additional notes to enable or disbable this restriction.

This MR updates the docs to reflect clarify that this is already default behavior.

Related issues

Original issue: #213159 (closed) FF removal: !49859 (merged)

The wording of the docs was brought up in slack.

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