FIXES JENKINS-18434 - Added validation error to Parameterized build choice, removed hard error.
Move check into ChoiceParameterDefinition.DescriptorImpl.
Revent changes to Jenkins and JenkinsTest.
Merge branch 'master' of github.com:jenkinsci/jenkins into JENKINS-18434
Merge pull request #968 from akiellor/JENKINS-18434
Noting #968
fixed broken localization (zh_CN)