Don't activate bevy_audio through android_shared_stdcxx

[NiklasEi]

Objective

• Make it easier to replace bevy_audio

Solution

Currently, the default_platform feature collection will activate bevy_audio through android_shared_stdcxx. This PR stops that.

Now, not adding the audio feature collection is enough to be able to use other audio solutions like bevy_seedling or bevy_kira_audio.

Testing

• Tested on Linux

[NiklasEi]

Duplicate of #22245 🙈