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
* Remove use of 0 in favor of `TrustLevel.levels[:newuser]`.
* Consolidate two tests into a single one.
* Test that disabling the feature works.
* Avoid loading full ActiveRecord object in test when we only need to
know the existence of the record.
Gerhard Schlager
Sam Saffron
Guo Xiang Tan
Bianca Nenciu