fix(button): use proper colors for the button states in the ionic theme (#30339)

Issue number: internal

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## What is the current behavior?
The focused and hover states are appearing as an overlay of the contrast
color on the buttons.

## What is the new behavior?
- Updates hover and focus states to match Figma designs
- Focus background should not change from the default
- Hover background should be the shade for solid buttons, and use
neutral subtlest for clear and outline buttons
- Updates the clear button to use the new `foreground` variant

## Does this introduce a breaking change?

- [ ] Yes
- [x] No