Buildah support

[astefanutti]

Following performance issues reported when using Kaniko on Minikube (#1204, #1209) and Vanilla k8s, and after investigation reported in GoogleContainerTools/kaniko#1013, I've PoC'ed using Buildah to build container images.

I've successfully build an integration image using the pod scheduling strategy and the quay.io/buildah/stable image. That PoC shows much better performance compared to that of Kaniko, and the image push to the local registry is under few seconds.

It seems also possible to use Buildah with the routine scheduling strategy (and the future service strategy #681), which simplifies caching. Combined with Maven dependencies caching, this seems the best approach to achieve integration build within few tens of seconds.

[kameshsampath]

@astefanutti do you have steps to test that ? I am also thinking if we can add a maven cache pod as part of the install that could be used with the integrations ???

[astefanutti]

@kameshsampath it's still a PoC but I'm confident it'll be available in the next release. Then we'll work on #681 which should enable to provide a Maven cache as part of the install.