Coordinate with App Bridge team for leave confirmation shake

[sophschneider]

App bridge next has shake but not app bridge host bc they have their own leave confirmation component

https://github.com/Shopify/app-bridge/blob/main/packages/app-bridge-host/src/components/ContextualSaveBar/LeaveConfirmation/LeaveConfirmation.tsx

This needs to be updated to use the new shake. Their team said they would do it but it will be after summer editions

More context https://github.com/Shopify/polaris-internal/issues/356