Improve perRow metric calculation

[maurever]

1. I found these changes very inefficient:

boolean score4Generic = m != null && m.getClass().toString().contains("Generic");

https://github.com/h2oai/h2o-3/pull/16025/commits/6421a819a0b634c331a06b6bbfa5838cd72b6f23

We should implement something like the method isGeneric() instead of comparing the name of the class with the hardwired String.

2. I also find this condition in ModelMetricBinomial is not usefull anymore:

https://github.com/h2oai/h2o-3/blob/2d8671d84f3bbed041ddc38387a15e85b3c8deb0/h2o-core/src/main/java/hex/ModelMetricsBinomial.java#L211

Because iact + 1 is always lower than ds.length for binomial cases.