Resize Dax logo in new tab page

[nalcalag]

Task/Issue URL: https://app.asana.com/0/0/1207453843423098/f

Description

Make new tab page Dax logo smaller

Steps to test this PR

• [ ] Fresh install
• [ ] Go to bbc.co.uk
• [ ] Dismiss trackers blocked onboarding dialog
• [ ] Open a new tab
• [ ] Perform a search
• [ ] Open a new tab
• [ ] Check Dax icon looks correct

UI changes

Before	After

[nalcalag]

• #4608 👈
• develop

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