Revert "Remove log_response_length feature flag"

What does this MR do and why?

Revert "Remove log_response_length feature flag"

This reverts commits 5ecf8069 and cd158c29. This introduced a regression for LFS file fetching when stored outside of object storage.

Has been confirmed as working on an install experiencing this issue: #419239 (comment 1504820342)

Changelog: fixed

Solves #419239 (closed)

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