GH-16590 Accept zero as offset for xgb models trained with offset

[Mathanraj-Sharma]

Fix #16590

xgb-Copy2.pdf

[valenad1]

LGTM, thank you!

Can you please rebase it on top of rel-3.46.0.

The base branch was changed.

[valenad1]

LGTM, thank you!

[Mathanraj-Sharma]

@valenad1 jenkins build is failing with below error, I guess it is irrelevant to the changes here

Found unhandled hudson.remoting.ProxyException exception:
jenkins.util.io.CompositeIOException: Unable to delete '/home/jenkins/workspace/H2O-3_h2o-3-ci-tests_PR-[1](http://jenkins.h2o.local:8080/job/H2O-3/job/h2o-3-ci-tests/job/PR-16605/3/pipeline-console/?start-byte=0&selected-node=19#log-1)6605/h2o-3'. Tried 3 times (of a maximum of 3) waiting 0.1 sec between attempts. (Discarded 20810 additional exceptions)
	Jenkins v2.495//jenkins.util.io.PathRemover.forceRemoveRecursive(PathRemover.java:96)
	Jenkins v2.495//hudson.Util.deleteRecursive(Util.java:334)
	Jenkins v[2](http://jenkins.h2o.local:8080/job/H2O-3/job/h2o-3-ci-tests/job/PR-16605/3/pipeline-console/?start-byte=0&selected-node=19#log-2).495//hudson.FilePath$DeleteRecursive.invoke(FilePath.java:1457)
	Jenkins v2.495//hudson.FilePath$DeleteRecursive.invoke(FilePath.java:1452)
	Jenkins v2.495//hudson.FilePath$FileCallableWrapper.call(FilePath.java:[3](http://jenkins.h2o.local:8080/job/H2O-3/job/h2o-3-ci-tests/job/PR-16605/3/pipeline-console/?start-byte=0&selected-node=19#log-3)593)
	hudson.remoting.UserRequest.perform(UserRequest.java:225)
	hudson.remoting.UserRequest.perform(UserRequest.java:50)
	hudson.remoting.Request$2.run(Request.java:391)
	hudson.remoting.InterceptingExecutorService.lambda$wrap$0(InterceptingExecutorService.java:81)
	java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
	java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:11[4](http://jenkins.h2o.local:8080/job/H2O-3/job/h2o-3-ci-tests/job/PR-16605/3/pipeline-console/?start-byte=0&selected-node=19#log-4)4)
	java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)