Changes in 0948d6b19e caused the post-bottom-ad component to start receiving the widget-ised 'transformedPost' instead of the original `post` model. In most cases this difference didn't matter, but it did cause noticable issues with `@model.category` and `@model.topic`.
This commit also deletes the unused `post-bottom/discourse-adplugin.hbs` connector. In the past, the adplugin itself was defining the post-bottom outlet. But now, we use RenderGlimmer to load the `post-bottom-ad` directly.
David Taylor