slimvariant that uses Debian slim and an Alpine variant for those who prefer Alpine
alpinetag is more likely what you want if you're seeking a minimal environment
plugins.txtfile that will allow you to build a Docker image where you have network access, then you can transport the created image into the environment that has no network access.
custom war packagerthat will create a custom war file that includes a set of plugins and other configurations. There is the Google Summer of Code project "Custom Jenkins distribution build service" currently running that is creating something that might be similar to what you're envisioning.