subtype: Remove `envout` code in intersection (#61449)

As far as I can tell this code is unused as envout is always computed in
subtype. I'm reworking this code and would prefer to remove it rather
than (possibly incorrectly) updating unused code.

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Co-authored-by: Keno Fischer <Keno@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>