fix(preferences, settings, atlas-service): ensure Atlas Login doesn't show in settings if user didn't get the Gen AI feature rollout

[gribnoysup]

No description provided.

[gribnoysup]

Now that we have a bunch of people logged in but with feature disabled I guess we can't really rely on login state be good enough indicator to show atlas login feature, even if it means that they wouldn't be able to log out manually

[addaleax]

fix: for the title? IIUC this is a behavioral change because we're changing the flag name, right?

[gribnoysup]

@addaleax good point, changed to fix and renamed so that it makes more sense in release notes

RE the renamed flags, I think we shouldn't break any existing behavior unless you explicitly disabled the feature (should be super rare right now). Because we noticed that we have this issue back where default preferences are stored on disk not allowing to change the default value, I'm renaming the enableGenAIExperience feature flag to make sure that it definitely picks up the new true default value. Another option that is part of the config file was added as a default true already, but just in case I'm renaming it too. In theory the only semi-publicly available option that we communicated so far was enableAIWithoutRolloutAccess and this stays the same

[gribnoysup]

I'll merge as the only test failing is the one that fails on main too and doesn't seem related