🐛 Bazaar: Settings in custom themes are not respected

### Plugin Name

bazaar

### 📜 Description

When using the backstage createUnifiedTheme the settings are not inherited by Bazaar. For example, changing the header image on each of the cards, does not update to match.

### 👍 Expected behavior

When you override settings in the unified theme, the styles are applied to Bazaar items.

### 👎 Actual Behavior with Screenshots

The custom themes are not respected.

### 👟 Reproduction steps

Install Bazaar, create a custom theme - all other addons will use the appropriate theme.

### 📃 Provide the context for the Bug.

_No response_

### 👀 Have you spent some time to check if this bug has been raised before?

- [X] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [X] I have read the [Code of Conduct](https://github.com/backstage/community-plugins/blob/main/CODE_OF_CONDUCT.md)

### Are you willing to submit PR?

None