fix(std): Correct hash_map max_load_percentage comparison

[kouosi]

since max_load_percentage is unsigned it will never be less then zero

[jeffective]

The existing implementation is just using a defensive programming pattern against future code changes.

The existing implementation is robust against the type changing to signed in the future (unlikely in this case, for sure), or the lower threshold changing as well. I think the existing pattern should remain as is.

[SeanTUT]

If anything, what strikes me as odd about the current code is that max_load_percentage is a u64. If we want to just represent (0, 100], it would be best to use u7, but if we want to allow whatever integer and validate ourselves, then we should be using comptime_int.