Incorrect clear button colour on dark mode focus in ic-select

### Summary of the bug
When using an ic-select component with a clear button in dark mode, the colour of the button appears incorrectly on focus. It currently appears dark but should appear white to contrast the focus colour.

### 🪜 How to reproduce
Tell us the steps to reproduce the problem:
1. Use an ic-select with a clear button in dark mode and select an item
2. Tab to focus on the clear button
3. See the error

### 📸 Screenshots or code
[Stackblitz](https://stackblitz.com/edit/uir8x8gp?file=index.html)

### 🧐 Expected behaviour
The button should appear light to contrast the focus colour, like with ic-search-bar:

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

Given an ic-select component using a clear button in dark mode
When clear button is in focus
Then clear button should appear white to contrast the background

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

Start with the ic-select component and reproduce the issue using the linked StackBlitz: enable its clear button, select an item, switch to dark mode, and tab to the clear button. Compare its focused appearance with ic-search-bar; done means the clear button appears white and contrasts with the focus colour in dark mode.

Written by the indexing model from the issue text.