Back off from successive requests when sync results in a 401

[Tyriar]

Currently it appears that when settings sync gets a 401 unauthorized it will continue to sync (and fail) on the standard interval. We should instead stop syncing immediately and show a warning that there is a problem with auth. If the server gives a 401 that means it's available and function and the token failed verification, it is guaranteed to continue to fail verification if the same token is used.

Related #85211 (this is more appropriate for 50x and 404s)

[gjsjohnmurray]

Looks like a dup of #86298

[Tyriar]

It is indeed lol, I thought it was a regression. Closing the other one as this has more info.

[sandy081]

I would not disable sync immediately in this case because auth token is managed by extension and so I would give some chances before stopping sync. Strategy that is followed in this case is mentioned here.

Reiterating here:

Error handling strategy:

• Sync is disabled automatically for specific errors (large resources - 413)

• Auto sync interval increases by number of failures every time there is an error (other than above)
• Sync is disabled when there are consecutive 5 failures

I think this should not happen, if happens it should be a bug some where (sync, auth or server)

[sandy081]

Fixed by a27c9fc