This investigation started because I noticed many timed out transactions in expiration, and one obvious thing here is we're sending notifications inside the transaction. So I'm moving those notifications out of the database transaction.

I'm also optimizing the exotic visits query, that is quite slow due to the LENGTH(url) check, so I am limiting it to urls with visit_count = 1.
While there, we could expire a little bit more, and non-typed hidden single-visit URIs look like an opportunity.
I'm finally increasing the time to 90 days, since there have been various requests to have a longer expiration time for downloads, this also makes the resultset to examine a bit smaller, helping with perf.

This included multiple changes:

1. Expire old non-typed hidden single-visit URIs
2. Expire long urls only if they are single-visit
3. increase the necessary age for expiration to 90 days
4. stop notifying listeners inside the database transaction

https://hg.mozilla.org/mozilla-central/rev/ae64c7092f40