Replace is_zero_approx(A.distance_to(B)) with A==B

[ptrojahn]

Related to #22988 (Fixes the holes in the shape of
the first comment)

[aaronfranke]

The reason this issue exists is that is_zero_approx is not actually the right thing to use here in the first place. Increasing the tolerance will only hide the true cause of the problem.

The purpose of this code is seems to be to check if the distance between two vectors is nearly zero. In other words, check if the vectors are approximately equal. Thanks to #18992, this is what the == operator does, so the fix should be if (segment[j] == points[i].point) {

There seem to be a lot of other places that have this problem, we can investigate using this command in Bash: grep -RIn distance_ | grep Math::is_zero_approx

[ptrojahn]

@aaronfranke Good idea! Didn't know == handles that.

[akien-mga]

Thanks!