Right now, the essentials-plugin changes are tested only using the standard buildPlugin.

We should have that, but then run at least the make container-check with the changed plugin to see if this does not break anything.

Note: I'm not doing that right now since 1) we have more pressing matters, and 2) possibly this will be superseded by a larger picture way of achieving this: we want any Jenkins Essentials change to be checked against evergreen tests and many many others, so maybe it's better and simpler to just see this plugin like any other Essentials one.

Any opinion rtyler?