Remove plugin-level auto-generation

[zstumgoren]

CommandHelpers.config auto-generates a plugin-level JSON file (see here).

This is surprising behavior -- not in the good way -- that causes confusion/errors downstream in plugins that rely on this mixin (See datakit-data for example).

Should change this behavior to require an explicit call to generate plugin-level configurations.

As part of implementation, must ensure that datakit-project does not rely on this auto-generation behavior.