[ic-card-horizontal] Subheading prop and adornment slot don't appear in playground

### Summary of the bug
Noticed that the subheading prop and the adornment slot don't appear in the horizontal card playground. They appear in Cypress tests and individual stories but for some reason aren't appearing the playground.

### 🪜 How to reproduce
Tell us the steps to reproduce the problem:
1. Go to horizontal card playground story
2. Change true and false value for adornment slot - see nothing changing
3. Change subheading value - see no subheading at all (not just that it's not changing)

### 📸 Screenshots or code

### 🧐 Expected behaviour
Every prop/slot should be covered in the playground.

### 🚨 Urgency (low, medium or high)
Low - from a quick look, it seems like it works everywhere else so it's just us it's impacting

Start with the horizontal card playground story and compare its setup with the individual stories and Cypress tests, where the subheading prop and adornment slot appear. Verify how the playground passes the true/false adornment value and subheading value. Done means both controls visibly render the corresponding content in the playground.

Written by the indexing model from the issue text.