[Navigation] Do not use travel cost for minimum when re-selecting end point

[sandygk]

This one liner PR fixes the bug, explained here #85238

Here is a screenshot of the same scene mentioned in the bug, but with the fix applied, please read the attached bug for an explanation of the issue and for a minimal project to test.

Bugsquad edit:

• Fixes Use min distance to target to re-select end point when the original end point is not reachable in navigation's path finding #85238

[AThousandShips]

Could you update your commit message (using git commit --amend and then pushing with git push --force) to be more descriptive, the minimum was always used, the change is in the value

The current title or similar would be good

[sandygk]

@AThousandShips done :)

[YuriSizov]

Thanks, and congrats on your first merged Godot contribution!