Secondary Button with Link hover colour

### Summary of the bug
Secondary buttons do not have correct colours on text and border when hovered over.

Slotted link text does not inherit the darkened colour on hover.

### 🪜 How to reproduce
Add a link within the button
[StackBlitz](https://stackblitz.com/edit/xuyspavu?file=index.html)

### 📸 Screenshots or code

### 🧐 Expected behaviour
Button with link should slightly change text colour, as show in regular secondary button

### 📝 Acceptance Criteria
If relevant, describe in full detail the different interactions and edge cases that the component or patterns needs to fulfil.

*Given*
*When*
*Then*

### 🚨 Urgency (low, medium or high)
Low

Start with the linked StackBlitz reproduction and trace the secondary button component’s hover styling, especially the slotted link text and border. Done when a button containing a link matches the regular secondary button’s hover text and border colours; verify both cases against the reproduction.

Written by the indexing model from the issue text.