Prefer comparisons in the absl::Time domain instead of the integer domain.

N.B.: In cases where an absl::Time is being converted to an integer, alignment may occur. If the comparison depends on this alignment, doing the comparison in the absl::Time domain may yield a different result. In practice this is very rare, and still indicates a bug which should be fixed.


// Original - Comparison in the integer domain
int x;
absl::Time t;
if (x < absl::ToUnixSeconds(t)) ...

// Suggested - Compare in the absl::Time domain instead
if (absl::FromUnixSeconds(x) < t) ...