Don't place busStop on a public_transport=stop_position

[Henry00572]

When a stop position on the road is tagged with highway=bus_stop + public_transport=stop_position there shouldn't be a bus stop shelter.

[Bauer33333]

highway=bus_stop marks the area where people wait for the bus, public_transport=stop_position the spot where the bus stops. These two tags describe two different things and so they shouldn't be on the same node. highway=bus_stop is not supposed to be tagged on roads since that would mean people are supposed to wait in the road, and even if that would be the case people can't wait at the exact spot where the bus is standing. So placing a shelter at every highway=bus_stop is not an issue, but those tags should be moved out of the road when you encounter them.

[Henry00572]

I know that it is generally not considered a valid tagging combination, however, according to taginfo, there are 193k elements with these two tags and the german wiki mentions this practice at DE:Tag:highway=bus_stop. Therefore, I think this variant can be seen as in use and the changes in this PR are relatively simple compared to retagging 190k objects.