Remove flag `enable_minor_delay_during_project_authorizations_refresh`"

What does this MR do and why?

This MR removes the feature flag enable_minor_delay_during_project_authorizations_refresh.

This flag has been enabled by default since 15.7, and there hasn't been any problems reported yet, so it is safe to remove this feature flag now.

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.

MR acceptance checklist

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

Related to #373672 (closed)