This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
It is not a setting, and only relevant in specs. The new API is:
```
Jobs.run_later! # jobs will be thrown on the queue
Jobs.run_immediately! # jobs will run right away, avoid the queue
```
Previously if you wanted to have jobs execute in test mode, you'd have
to do `SiteSetting.queue_jobs = false`, because the opposite of queue
is to execute.
I found this very confusing, so I created a test helper called
`run_jobs_synchronously!` which is much more clear about what it does.
