Option to disable load boundary cutoff only when backtrack cost favoring executes!!

[leijurv]

This gets you the best of both worlds, with regards to path safety and optimality (i.e. having load boundary cutoff on for most of the time), but still preventing oscillation (between the best loaded point, and the cache-edge of the workaround path) if a backtrack beyond the load boundary is required (which happens ALL THE TIME in 2b2t spawn lol), because a backtrack DISABLES load boundary cutoff! And yet we still have all the safeguards (cost verification lookahead, maximum cost increase limits, etc) to make that one-time cached path safe. I think cutoffAtLoadBoundary should default to false, but if you turn it on, there should be a second option, defaulting to true, that overrides that cutoff to false if the best path involved any backtracking.

[leijurv]

This is still a good idea, but cutoffAtLoadBoundary defaults to false now, so it won't really have any effect on anyone...