Remove core/video and core/audio features that don't correlate correctly.

We are handling the availability of some blocks through the `core/audio` and `core/video` features. As we explain in [this PR,](https://github.com/Automattic/jetpack/pull/20478) relying on these features may not be a good idea. Consider removing and replacing them with more accurate features.

Start by reading the linked PR #20478 and locating where the core/audio and core/video features control block availability. Identify the more accurate replacement features and confirm all affected checks are covered; done means those two features no longer determine availability incorrectly.

Written by the indexing model from the issue text.