ran `yarn flow-all`. Since cookie was not being used since the previous diff, this should be enough
EDIT:
tested that the cookie was migrated on native:
- checked out master, opened the app, logged the cookie
- closed the app
- checked out this diff, opened the app, logged the cookie
On master, rehyderated keys included `cookie`. On this diff, rehydrated keys don't include 'cookie', but include the `keyserverStore`. Checked that `cookie` that was logged on master is equal to the `keyserverStore.keyserverInfos['256'].cookie` on this diff