Adjust goal heuristic based on whether or not sprinting is possible

Walking is 4.63 ticks per block, and sprinting is 3.56.

If sprinting is allowed, any heuristic greater than 3.56 is an overestimate.
The default is 3.5 right now.

However, if you can't sprint, this is such an underestimate that pathing becomes practically very difficult and almost Dijkstra-like.

It should be 3.5 when sprinting is possible, and 4.6 otherwise.

Start by locating the goal heuristic used by the pathfinding algorithm and trace how sprinting availability is represented. Verify the heuristic value when sprinting is possible versus when it is not, and confirm that pathing uses 3.5 and 4.6 respectively.

Written by the indexing model from the issue text.