* configure jobs as code (https://wiki.jenkins-ci.org/display/JENKINS/Job+DSL+Plugin)
* system configuration as code (https://issues.jenkins-ci.org/browse/JENKINS-31094) and its current prototype (https://github.com/jenkinsci/system-config-dsl-plugin)
* bypassing setup wizard (https://issues.jenkins-ci.org/browse/JENKINS-34035)
There are also puppet modules, Chef cookbooks, and etc that a lot of people use. Some of those are maintained by people who are also in the Jenkins community, so I don't consider them "3rd party hacks" if you are referring to those.