Follow up from https://github.com/matomo-org/matomo-package/pull/112
It's been a while since we released Matomo 4 meaning we can now remove Provider and CustomVariables plugin from the core release and only ship it only through the marketplace.
We no longer want to have in
matomo.zip release zip the directories
plugins/CustomVariables. Of course we also need to test that this won't cause any issues for people that are already on Matomo 4.