Enable FxA state encryption for release

[grigoryk]

#5938 enabled account state encryption for nightly users.

Things to watch out for in Sentry:

• instances of AbnormalFxaEvent, specifically MissingExpectedAccountAfterStartup
• instances of AbnormalAccountStorageEvent@UnexpectedlyMissingAccountState

If we don't see a spike in these after a few weeks, let's consider flipping encrypted storage for the release channels.

Acceptance Criteria

• Look on Sentry and verify that there are not a lot of the highlighted issues. If there are, file and prioritize them.
• Enable FxA state encryption on release

┆Issue is synchronized with this Jira Task

[grigoryk]

Note that there's currently some volume of MissingExpectedAccountAfterStartup. I expect those to drop to zero once mozilla-mobile/android-components#5103 makes its way to nightly users.

[grigoryk]

There was a non-zero volume of Android KeyStore related crashes in Sentry. This needs more investigation.

[liuche]

Not seeing many crashes for AbnormalFxaEvent$MissingExpectedAccountAfterStartup on Nightly, which peaked Jan 11 with the Login startup crash, and then has trended back down. Not many crashes on Sentry either.

This is probably fine to turn on at this point.

[ValentinTimisica]

Based on this comment I understand that FxA state encryption needs to be enabled for all channels. So I made a PR where I set secureStateAtRest = true. @grigoryk is this correct?
If it needs to be enabled just for Nightly and Release I will change it accordingly.

[ekager]

We've decided to wait a bit longer to enable for all channels see #8324

[ekager]

Didn't mean to close the issue

[liuche]

We'll do this after release, based on some concerns about a low number of crashes #8324 and how this would affect Fennec Release population devices. This is probably low because the Fenix release population is already using the system keystore, but to be safe we'll turn this on as an experiment rollout after our release.

[liuche]

@grigoryk do we still care about this bug

[stale]

See: #17373 This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.