feat(log): unhide `tracing::instrument` from behind `feature = "otel"`

[rami3l]

Cherry-picked from #3803 as discussed in https://github.com/rust-lang/rustup/pull/3803#issuecomment-2168125917.

Note

This is done by simply replacing #[cfg_attr\(feature = \"otel\", tracing:: instrument(\((.*)\))?\)\] with #[tracing::instrument(level = "trace", $2)].