Once they're finalized, add assets for the new MR onboarding 50-50 template design and ensure they're displayed for users with the new template enabled.

Assets include:

• Background illustration
• New Firefox logo

UX confirmed we can use this existing arrow asset for secondary CTA : https://searchfox.org/mozilla-central/source/browser/themes/shared/icons/forward.svg (this is now covered in bug 1781528)

NI @Ania to update bug with final assets

Here's the folder with final assets.
I'll clear the needinfo a little later tonight after we finish the very final tweaks on the images and add them to the folder.

All svgs are uploaded!

Backed out for causing failures at browser_parsable_css.js.

Backout link: https://hg.mozilla.org/integration/autoland/rev/dc383b62f43dafef3f0010d236d5ce8af5ff562c

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=AeqUyTBqSpCXpkoax2T60Q.0&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=9256826198bb8dda01ccf49b74a1c36e87a08059

Failure log: https://treeherder.mozilla.org/logviewer?job_id=388979408&repo=autoland&lineNumber=1881

https://hg.mozilla.org/mozilla-central/rev/ca8f3afc3391

I have verified this task and I can confirm the background images from the "about:welcome" screens and the upgrade modals respect the Figma specifications.

Verified using the latest Firefox Nightly (106.0a1 Build ID - 20220831093258) installed on Windows 10 x64, macOS 11.6.5, and Linux Mint 20.2 x64.

Thanks @mardak for re-landing!